OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: exp(7*Sum_{j>=1} Sum_{k>=1} (-1)^(j+1)*k^j*x^(j*k)/j). - Ilya Gutkovskiy, Feb 08 2018
MATHEMATICA
With[{nmax = 50}, CoefficientList[Series[Product[(1 + k*q^k)^7, {k, 1, nmax}], {q, 0, nmax}], q]] (* G. C. Greubel, Feb 17 2018 *)
PROG
(PARI) m=50; q='q+O('q^m); Vec(prod(n=1, m, (1+n*q^n)^7)) \\ G. C. Greubel, Feb 17 2018
(Magma) Coefficients(&*[(1+m*x^m)^7:m in [1..40]])[1..40] where x is PolynomialRing(Integers()).1; // G. C. Greubel, Feb 17 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved