OFFSET
1,3
MATHEMATICA
a[1] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, d] a[(n - 1)/d], {d, Divisors[n - 1]}]; Table[a[n], {n, 1, 23}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jul 09 2021
STATUS
approved