OFFSET
1,5
MATHEMATICA
a[1] = a[2] = 1; a[n_] := a[n] = Sum[If[d < (n - 1), a[(n - 1)/d] a[d], 0], {d, Divisors[n - 1]}]; Table[a[n], {n, 60}]
PROG
(PARI) A341697(n) = if(n<3, 1, sumdiv(n-1, d, if(d<(n-1), A341697((n-1)/d)*A341697(d), 0))); \\ Antti Karttunen, Feb 17 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 17 2021
STATUS
approved