OFFSET
0,4
FORMULA
MATHEMATICA
a[0] = 1; a[n_] := a[n] = Sum[DivisorSum[k, #^(# + 1) &, OddQ[#] &]*a[n - k], {k, 1, n}]/n; Array[a, 20, 0] (* Amiram Eldar, Jul 09 2023 *)
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(1/prod(k=1, N, (1-x^(2*k-1))^((2*k-1)^(2*k-1))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 09 2023
STATUS
approved