OFFSET
0,3
LINKS
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Euler Transform
FORMULA
G.f.: Product_{k>=1} 1/(1 - x^k)^sigma(k,k).
a(n) = (1/n)*Sum_{k=1..n} a(n-k)*b(k) for n>1, a(0)=1, where b(k) = Sum_{d|k} d*sigma(d,d).
MATHEMATICA
a = Table[DivisorSigma[n, n], {n, 20}]; CoefficientList[Series[Product[1/(1 - x^m)^a[[m]], {m, 20}], {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Apr 28 2023
STATUS
approved