3.1.84 \(\int \frac {(e x)^{-1+3 n}}{(a+b \text {sech}(c+d x^n))^2} \, dx\) [84]

3.1.84.1 Optimal result
3.1.84.2 Mathematica [F]
3.1.84.3 Rubi [A] (verified)
3.1.84.4 Maple [F]
3.1.84.5 Fricas [F(-1)]
3.1.84.6 Sympy [F]
3.1.84.7 Maxima [F]
3.1.84.8 Giac [F]
3.1.84.9 Mupad [F(-1)]

3.1.84.1 Optimal result

Integrand size = 24, antiderivative size = 1284 \[ \int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx=\frac {(e x)^{3 n}}{3 a^2 e n}+\frac {b^2 x^{-n} (e x)^{3 n}}{a^2 \left (a^2-b^2\right ) d e n}-\frac {2 b^2 x^{-2 n} (e x)^{3 n} \log \left (1+\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \left (a^2-b^2\right ) d^2 e n}+\frac {b^3 x^{-n} (e x)^{3 n} \log \left (1+\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \left (-a^2+b^2\right )^{3/2} d e n}-\frac {2 b x^{-n} (e x)^{3 n} \log \left (1+\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \sqrt {-a^2+b^2} d e n}-\frac {2 b^2 x^{-2 n} (e x)^{3 n} \log \left (1+\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \left (a^2-b^2\right ) d^2 e n}-\frac {b^3 x^{-n} (e x)^{3 n} \log \left (1+\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \left (-a^2+b^2\right )^{3/2} d e n}+\frac {2 b x^{-n} (e x)^{3 n} \log \left (1+\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \sqrt {-a^2+b^2} d e n}-\frac {2 b^2 x^{-3 n} (e x)^{3 n} \operatorname {PolyLog}\left (2,-\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \left (a^2-b^2\right ) d^3 e n}+\frac {2 b^3 x^{-2 n} (e x)^{3 n} \operatorname {PolyLog}\left (2,-\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \left (-a^2+b^2\right )^{3/2} d^2 e n}-\frac {4 b x^{-2 n} (e x)^{3 n} \operatorname {PolyLog}\left (2,-\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \sqrt {-a^2+b^2} d^2 e n}-\frac {2 b^2 x^{-3 n} (e x)^{3 n} \operatorname {PolyLog}\left (2,-\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \left (a^2-b^2\right ) d^3 e n}-\frac {2 b^3 x^{-2 n} (e x)^{3 n} \operatorname {PolyLog}\left (2,-\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \left (-a^2+b^2\right )^{3/2} d^2 e n}+\frac {4 b x^{-2 n} (e x)^{3 n} \operatorname {PolyLog}\left (2,-\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \sqrt {-a^2+b^2} d^2 e n}-\frac {2 b^3 x^{-3 n} (e x)^{3 n} \operatorname {PolyLog}\left (3,-\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \left (-a^2+b^2\right )^{3/2} d^3 e n}+\frac {4 b x^{-3 n} (e x)^{3 n} \operatorname {PolyLog}\left (3,-\frac {a e^{c+d x^n}}{b-\sqrt {-a^2+b^2}}\right )}{a^2 \sqrt {-a^2+b^2} d^3 e n}+\frac {2 b^3 x^{-3 n} (e x)^{3 n} \operatorname {PolyLog}\left (3,-\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \left (-a^2+b^2\right )^{3/2} d^3 e n}-\frac {4 b x^{-3 n} (e x)^{3 n} \operatorname {PolyLog}\left (3,-\frac {a e^{c+d x^n}}{b+\sqrt {-a^2+b^2}}\right )}{a^2 \sqrt {-a^2+b^2} d^3 e n}+\frac {b^2 x^{-n} (e x)^{3 n} \sinh \left (c+d x^n\right )}{a \left (a^2-b^2\right ) d e n \left (b+a \cosh \left (c+d x^n\right )\right )} \]

output
1/3*(e*x)^(3*n)/a^2/e/n+b^2*(e*x)^(3*n)/a^2/(a^2-b^2)/d/e/n/(x^n)-2*b^2*(e 
*x)^(3*n)*ln(1+a*exp(c+d*x^n)/(b-(-a^2+b^2)^(1/2)))/a^2/(a^2-b^2)/d^2/e/n/ 
(x^(2*n))+b^3*(e*x)^(3*n)*ln(1+a*exp(c+d*x^n)/(b-(-a^2+b^2)^(1/2)))/a^2/(- 
a^2+b^2)^(3/2)/d/e/n/(x^n)-2*b^2*(e*x)^(3*n)*ln(1+a*exp(c+d*x^n)/(b+(-a^2+ 
b^2)^(1/2)))/a^2/(a^2-b^2)/d^2/e/n/(x^(2*n))-b^3*(e*x)^(3*n)*ln(1+a*exp(c+ 
d*x^n)/(b+(-a^2+b^2)^(1/2)))/a^2/(-a^2+b^2)^(3/2)/d/e/n/(x^n)-2*b^2*(e*x)^ 
(3*n)*polylog(2,-a*exp(c+d*x^n)/(b-(-a^2+b^2)^(1/2)))/a^2/(a^2-b^2)/d^3/e/ 
n/(x^(3*n))+2*b^3*(e*x)^(3*n)*polylog(2,-a*exp(c+d*x^n)/(b-(-a^2+b^2)^(1/2 
)))/a^2/(-a^2+b^2)^(3/2)/d^2/e/n/(x^(2*n))-2*b^2*(e*x)^(3*n)*polylog(2,-a* 
exp(c+d*x^n)/(b+(-a^2+b^2)^(1/2)))/a^2/(a^2-b^2)/d^3/e/n/(x^(3*n))-2*b^3*( 
e*x)^(3*n)*polylog(2,-a*exp(c+d*x^n)/(b+(-a^2+b^2)^(1/2)))/a^2/(-a^2+b^2)^ 
(3/2)/d^2/e/n/(x^(2*n))-2*b^3*(e*x)^(3*n)*polylog(3,-a*exp(c+d*x^n)/(b-(-a 
^2+b^2)^(1/2)))/a^2/(-a^2+b^2)^(3/2)/d^3/e/n/(x^(3*n))+2*b^3*(e*x)^(3*n)*p 
olylog(3,-a*exp(c+d*x^n)/(b+(-a^2+b^2)^(1/2)))/a^2/(-a^2+b^2)^(3/2)/d^3/e/ 
n/(x^(3*n))+b^2*(e*x)^(3*n)*sinh(c+d*x^n)/a/(a^2-b^2)/d/e/n/(x^n)/(b+a*cos 
h(c+d*x^n))-2*b*(e*x)^(3*n)*ln(1+a*exp(c+d*x^n)/(b-(-a^2+b^2)^(1/2)))/a^2/ 
d/e/n/(x^n)/(-a^2+b^2)^(1/2)+2*b*(e*x)^(3*n)*ln(1+a*exp(c+d*x^n)/(b+(-a^2+ 
b^2)^(1/2)))/a^2/d/e/n/(x^n)/(-a^2+b^2)^(1/2)-4*b*(e*x)^(3*n)*polylog(2,-a 
*exp(c+d*x^n)/(b-(-a^2+b^2)^(1/2)))/a^2/d^2/e/n/(x^(2*n))/(-a^2+b^2)^(1/2) 
+4*b*(e*x)^(3*n)*polylog(2,-a*exp(c+d*x^n)/(b+(-a^2+b^2)^(1/2)))/a^2/d^...
 
3.1.84.2 Mathematica [F]

\[ \int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx=\int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx \]

input
Integrate[(e*x)^(-1 + 3*n)/(a + b*Sech[c + d*x^n])^2,x]
 
output
Integrate[(e*x)^(-1 + 3*n)/(a + b*Sech[c + d*x^n])^2, x]
 
3.1.84.3 Rubi [A] (verified)

Time = 2.27 (sec) , antiderivative size = 1019, normalized size of antiderivative = 0.79, number of steps used = 6, number of rules used = 5, \(\frac {\text {number of rules}}{\text {integrand size}}\) = 0.208, Rules used = {5963, 5959, 3042, 4679, 2009}

Below are the steps used by Rubi to obtain the solution. The rule number used for the transformation is given above next to the arrow. The rules definitions used are listed below.

\(\displaystyle \int \frac {(e x)^{3 n-1}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx\)

\(\Big \downarrow \) 5963

\(\displaystyle \frac {x^{-3 n} (e x)^{3 n} \int \frac {x^{3 n-1}}{\left (a+b \text {sech}\left (d x^n+c\right )\right )^2}dx}{e}\)

\(\Big \downarrow \) 5959

\(\displaystyle \frac {x^{-3 n} (e x)^{3 n} \int \frac {x^{2 n}}{\left (a+b \text {sech}\left (d x^n+c\right )\right )^2}dx^n}{e n}\)

\(\Big \downarrow \) 3042

\(\displaystyle \frac {x^{-3 n} (e x)^{3 n} \int \frac {x^{2 n}}{\left (a+b \csc \left (i d x^n+i c+\frac {\pi }{2}\right )\right )^2}dx^n}{e n}\)

\(\Big \downarrow \) 4679

\(\displaystyle \frac {x^{-3 n} (e x)^{3 n} \int \left (-\frac {2 b x^{2 n}}{a^2 \left (b+a \cosh \left (d x^n+c\right )\right )}+\frac {x^{2 n}}{a^2}+\frac {b^2 x^{2 n}}{a^2 \left (b+a \cosh \left (d x^n+c\right )\right )^2}\right )dx^n}{e n}\)

\(\Big \downarrow \) 2009

\(\displaystyle \frac {x^{-3 n} (e x)^{3 n} \left (-\frac {2 b^2 \log \left (\frac {e^{d x^n+c} a}{b-\sqrt {b^2-a^2}}+1\right ) x^n}{a^2 \left (a^2-b^2\right ) d^2}-\frac {2 b^2 \log \left (\frac {e^{d x^n+c} a}{b+\sqrt {b^2-a^2}}+1\right ) x^n}{a^2 \left (a^2-b^2\right ) d^2}-\frac {4 b \operatorname {PolyLog}\left (2,-\frac {a e^{d x^n+c}}{b-\sqrt {b^2-a^2}}\right ) x^n}{a^2 \sqrt {b^2-a^2} d^2}+\frac {2 b^3 \operatorname {PolyLog}\left (2,-\frac {a e^{d x^n+c}}{b-\sqrt {b^2-a^2}}\right ) x^n}{a^2 \left (b^2-a^2\right )^{3/2} d^2}+\frac {4 b \operatorname {PolyLog}\left (2,-\frac {a e^{d x^n+c}}{b+\sqrt {b^2-a^2}}\right ) x^n}{a^2 \sqrt {b^2-a^2} d^2}-\frac {2 b^3 \operatorname {PolyLog}\left (2,-\frac {a e^{d x^n+c}}{b+\sqrt {b^2-a^2}}\right ) x^n}{a^2 \left (b^2-a^2\right )^{3/2} d^2}-\frac {2 b \log \left (\frac {e^{d x^n+c} a}{b-\sqrt {b^2-a^2}}+1\right ) x^{2 n}}{a^2 \sqrt {b^2-a^2} d}+\frac {b^3 \log \left (\frac {e^{d x^n+c} a}{b-\sqrt {b^2-a^2}}+1\right ) x^{2 n}}{a^2 \left (b^2-a^2\right )^{3/2} d}+\frac {2 b \log \left (\frac {e^{d x^n+c} a}{b+\sqrt {b^2-a^2}}+1\right ) x^{2 n}}{a^2 \sqrt {b^2-a^2} d}-\frac {b^3 \log \left (\frac {e^{d x^n+c} a}{b+\sqrt {b^2-a^2}}+1\right ) x^{2 n}}{a^2 \left (b^2-a^2\right )^{3/2} d}+\frac {b^2 \sinh \left (d x^n+c\right ) x^{2 n}}{a \left (a^2-b^2\right ) d \left (b+a \cosh \left (d x^n+c\right )\right )}+\frac {b^2 x^{2 n}}{a^2 \left (a^2-b^2\right ) d}+\frac {x^{3 n}}{3 a^2}-\frac {2 b^2 \operatorname {PolyLog}\left (2,-\frac {a e^{d x^n+c}}{b-\sqrt {b^2-a^2}}\right )}{a^2 \left (a^2-b^2\right ) d^3}-\frac {2 b^2 \operatorname {PolyLog}\left (2,-\frac {a e^{d x^n+c}}{b+\sqrt {b^2-a^2}}\right )}{a^2 \left (a^2-b^2\right ) d^3}+\frac {4 b \operatorname {PolyLog}\left (3,-\frac {a e^{d x^n+c}}{b-\sqrt {b^2-a^2}}\right )}{a^2 \sqrt {b^2-a^2} d^3}-\frac {2 b^3 \operatorname {PolyLog}\left (3,-\frac {a e^{d x^n+c}}{b-\sqrt {b^2-a^2}}\right )}{a^2 \left (b^2-a^2\right )^{3/2} d^3}-\frac {4 b \operatorname {PolyLog}\left (3,-\frac {a e^{d x^n+c}}{b+\sqrt {b^2-a^2}}\right )}{a^2 \sqrt {b^2-a^2} d^3}+\frac {2 b^3 \operatorname {PolyLog}\left (3,-\frac {a e^{d x^n+c}}{b+\sqrt {b^2-a^2}}\right )}{a^2 \left (b^2-a^2\right )^{3/2} d^3}\right )}{e n}\)

input
Int[(e*x)^(-1 + 3*n)/(a + b*Sech[c + d*x^n])^2,x]
 
output
((e*x)^(3*n)*((b^2*x^(2*n))/(a^2*(a^2 - b^2)*d) + x^(3*n)/(3*a^2) - (2*b^2 
*x^n*Log[1 + (a*E^(c + d*x^n))/(b - Sqrt[-a^2 + b^2])])/(a^2*(a^2 - b^2)*d 
^2) + (b^3*x^(2*n)*Log[1 + (a*E^(c + d*x^n))/(b - Sqrt[-a^2 + b^2])])/(a^2 
*(-a^2 + b^2)^(3/2)*d) - (2*b*x^(2*n)*Log[1 + (a*E^(c + d*x^n))/(b - Sqrt[ 
-a^2 + b^2])])/(a^2*Sqrt[-a^2 + b^2]*d) - (2*b^2*x^n*Log[1 + (a*E^(c + d*x 
^n))/(b + Sqrt[-a^2 + b^2])])/(a^2*(a^2 - b^2)*d^2) - (b^3*x^(2*n)*Log[1 + 
 (a*E^(c + d*x^n))/(b + Sqrt[-a^2 + b^2])])/(a^2*(-a^2 + b^2)^(3/2)*d) + ( 
2*b*x^(2*n)*Log[1 + (a*E^(c + d*x^n))/(b + Sqrt[-a^2 + b^2])])/(a^2*Sqrt[- 
a^2 + b^2]*d) - (2*b^2*PolyLog[2, -((a*E^(c + d*x^n))/(b - Sqrt[-a^2 + b^2 
]))])/(a^2*(a^2 - b^2)*d^3) + (2*b^3*x^n*PolyLog[2, -((a*E^(c + d*x^n))/(b 
 - Sqrt[-a^2 + b^2]))])/(a^2*(-a^2 + b^2)^(3/2)*d^2) - (4*b*x^n*PolyLog[2, 
 -((a*E^(c + d*x^n))/(b - Sqrt[-a^2 + b^2]))])/(a^2*Sqrt[-a^2 + b^2]*d^2) 
- (2*b^2*PolyLog[2, -((a*E^(c + d*x^n))/(b + Sqrt[-a^2 + b^2]))])/(a^2*(a^ 
2 - b^2)*d^3) - (2*b^3*x^n*PolyLog[2, -((a*E^(c + d*x^n))/(b + Sqrt[-a^2 + 
 b^2]))])/(a^2*(-a^2 + b^2)^(3/2)*d^2) + (4*b*x^n*PolyLog[2, -((a*E^(c + d 
*x^n))/(b + Sqrt[-a^2 + b^2]))])/(a^2*Sqrt[-a^2 + b^2]*d^2) - (2*b^3*PolyL 
og[3, -((a*E^(c + d*x^n))/(b - Sqrt[-a^2 + b^2]))])/(a^2*(-a^2 + b^2)^(3/2 
)*d^3) + (4*b*PolyLog[3, -((a*E^(c + d*x^n))/(b - Sqrt[-a^2 + b^2]))])/(a^ 
2*Sqrt[-a^2 + b^2]*d^3) + (2*b^3*PolyLog[3, -((a*E^(c + d*x^n))/(b + Sqrt[ 
-a^2 + b^2]))])/(a^2*(-a^2 + b^2)^(3/2)*d^3) - (4*b*PolyLog[3, -((a*E^(...
 

3.1.84.3.1 Defintions of rubi rules used

rule 2009
Int[u_, x_Symbol] :> Simp[IntSum[u, x], x] /; SumQ[u]
 

rule 3042
Int[u_, x_Symbol] :> Int[DeactivateTrig[u, x], x] /; FunctionOfTrigOfLinear 
Q[u, x]
 

rule 4679
Int[(csc[(e_.) + (f_.)*(x_)]*(b_.) + (a_))^(n_.)*((c_.) + (d_.)*(x_))^(m_.) 
, x_Symbol] :> Int[ExpandIntegrand[(c + d*x)^m, 1/(Sin[e + f*x]^n/(b + a*Si 
n[e + f*x])^n), x], x] /; FreeQ[{a, b, c, d, e, f}, x] && ILtQ[n, 0] && IGt 
Q[m, 0]
 

rule 5959
Int[(x_)^(m_.)*((a_.) + (b_.)*Sech[(c_.) + (d_.)*(x_)^(n_)])^(p_.), x_Symbo 
l] :> Simp[1/n   Subst[Int[x^(Simplify[(m + 1)/n] - 1)*(a + b*Sech[c + d*x] 
)^p, x], x, x^n], x] /; FreeQ[{a, b, c, d, m, n, p}, x] && IGtQ[Simplify[(m 
 + 1)/n], 0] && IntegerQ[p]
 

rule 5963
Int[((e_)*(x_))^(m_.)*((a_.) + (b_.)*Sech[(c_.) + (d_.)*(x_)^(n_)])^(p_.), 
x_Symbol] :> Simp[e^IntPart[m]*((e*x)^FracPart[m]/x^FracPart[m])   Int[x^m* 
(a + b*Sech[c + d*x^n])^p, x], x] /; FreeQ[{a, b, c, d, e, m, n, p}, x]
 
3.1.84.4 Maple [F]

\[\int \frac {\left (e x \right )^{-1+3 n}}{{\left (a +b \,\operatorname {sech}\left (c +d \,x^{n}\right )\right )}^{2}}d x\]

input
int((e*x)^(-1+3*n)/(a+b*sech(c+d*x^n))^2,x)
 
output
int((e*x)^(-1+3*n)/(a+b*sech(c+d*x^n))^2,x)
 
3.1.84.5 Fricas [F(-1)]

Timed out. \[ \int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx=\text {Timed out} \]

input
integrate((e*x)^(-1+3*n)/(a+b*sech(c+d*x^n))^2,x, algorithm="fricas")
 
output
Timed out
 
3.1.84.6 Sympy [F]

\[ \int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx=\int \frac {\left (e x\right )^{3 n - 1}}{\left (a + b \operatorname {sech}{\left (c + d x^{n} \right )}\right )^{2}}\, dx \]

input
integrate((e*x)**(-1+3*n)/(a+b*sech(c+d*x**n))**2,x)
 
output
Integral((e*x)**(3*n - 1)/(a + b*sech(c + d*x**n))**2, x)
 
3.1.84.7 Maxima [F]

\[ \int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx=\int { \frac {\left (e x\right )^{3 \, n - 1}}{{\left (b \operatorname {sech}\left (d x^{n} + c\right ) + a\right )}^{2}} \,d x } \]

input
integrate((e*x)^(-1+3*n)/(a+b*sech(c+d*x^n))^2,x, algorithm="maxima")
 
output
-1/3*(6*a*b^2*e^(3*n)*x^(2*n) - (a^3*d*e^(3*n) - a*b^2*d*e^(3*n))*x^(3*n) 
- (a^3*d*e^(3*n)*e^(2*c) - a*b^2*d*e^(3*n)*e^(2*c))*e^(2*d*x^n + 3*n*log(x 
)) + 2*(3*b^3*e^(3*n)*e^(2*n*log(x) + c) - (a^2*b*d*e^(3*n)*e^c - b^3*d*e^ 
(3*n)*e^c)*x^(3*n))*e^(d*x^n))/(a^5*d*e*n - a^3*b^2*d*e*n + (a^5*d*e*n*e^( 
2*c) - a^3*b^2*d*e*n*e^(2*c))*e^(2*d*x^n) + 2*(a^4*b*d*e*n*e^c - a^2*b^3*d 
*e*n*e^c)*e^(d*x^n)) - integrate(-2*(2*a*b^2*e^(3*n)*x^(2*n) + (2*b^3*e^(3 
*n)*e^(2*n*log(x) + c) - (2*a^2*b*d*e^(3*n)*e^c - b^3*d*e^(3*n)*e^c)*x^(3* 
n))*e^(d*x^n))/((a^5*d*e*e^(2*c) - a^3*b^2*d*e*e^(2*c))*x*e^(2*d*x^n) + 2* 
(a^4*b*d*e*e^c - a^2*b^3*d*e*e^c)*x*e^(d*x^n) + (a^5*d*e - a^3*b^2*d*e)*x) 
, x)
 
3.1.84.8 Giac [F]

\[ \int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx=\int { \frac {\left (e x\right )^{3 \, n - 1}}{{\left (b \operatorname {sech}\left (d x^{n} + c\right ) + a\right )}^{2}} \,d x } \]

input
integrate((e*x)^(-1+3*n)/(a+b*sech(c+d*x^n))^2,x, algorithm="giac")
 
output
integrate((e*x)^(3*n - 1)/(b*sech(d*x^n + c) + a)^2, x)
 
3.1.84.9 Mupad [F(-1)]

Timed out. \[ \int \frac {(e x)^{-1+3 n}}{\left (a+b \text {sech}\left (c+d x^n\right )\right )^2} \, dx=\int \frac {{\left (e\,x\right )}^{3\,n-1}}{{\left (a+\frac {b}{\mathrm {cosh}\left (c+d\,x^n\right )}\right )}^2} \,d x \]

input
int((e*x)^(3*n - 1)/(a + b/cosh(c + d*x^n))^2,x)
 
output
int((e*x)^(3*n - 1)/(a + b/cosh(c + d*x^n))^2, x)