OFFSET
1,2
FORMULA
Product_{n>=1} 1 / (1 - a(n)*x^n) = 1 + Sum_{n>=1} x^n / (1 - x^n)^2.
MATHEMATICA
A[m_, n_] := A[m, n] = Which[m == 1, DivisorSigma[1, n], m > n >= 1, 0, True, A[m - 1, n] - A[m - 1, m - 1] A[m - 1, n - m + 1]]; a[n_] := A[n, n]; a /@ Range[1, 50]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, May 12 2022
STATUS
approved