APowerBesideAnExponentialOfAPower​(AngouriMath.​Entity,​AngouriMath.​Entity.​Variable,​System.​Boolean)

int x^m F^(a + b x^n) dx, and int (c + d x)^m F^(a + b x) dx, where the integral is a gamma
function of s = (m + 1)/n, for an s neither whole nor half a whole number -- where it is
elementary, an exponential integral or an error function, and those are answered as such -- or not a
number at all. With z = -b ln(F) x^n, x^(m + 1) z^(-s) is constant between the cuts and
Gamma(s, z) differentiates to -z^(s - 1) e^(-z) z', so the first is
-F^a x^(m + 1) z^(-s) Gamma(s, z)/n; the second is the first with n = 1 under
t = c + d x. Several exponentials are read as one, and terms of one degree in the exponent as one term:
f^(a + b x^n) g^(c + d x^n) is e^(a ln f + c ln g + (b ln f + d ln g) x^n). Rubi's 2.3.
https://github.com/asc-community/AngouriMath/issues/2075