A321057 a(n) = [x^n] Product_{k>=1} ((1 + x^k)/(1 - x^k))^sigma_n(k).

1, 2, 12, 94, 1522, 48154, 3087600, 377880794, 93356591804, 46415548879976, 44773963087975388, 86770399797767582434, 340765670578000502365102, 2625605734866823121935402410, 40755373130582885082115865730892, 1290109927277547765958474680645604818

Offset: 0

Author

Seiichi Manyama, Oct 26 2018

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..80

Crossrefs

Cf. A301554, A301555, A301556, A319647, A321042, A321068.

Programs

Mathematica

Table[SeriesCoefficient[Product[((1 + x^k)/(1 - x^k))^DivisorSigma[n, k], {k, 1, n}], {x, 0, n}], {n, 0, 15}] (* Vaclav Kotesovec, Oct 27 2018 *)

PARI

{a(n) = polcoeff(prod(k=1, n, ((1+x^k+x*O(x^n))/(1-x^k+x*O(x^n)))^sigma(k, n)), n)}