OFFSET
1,3
FORMULA
a(1) = 0; a(n) = (n-1)! * (1 - Sum_{d|n, 1 < d < n} d * (a(d)/d!)^(n/d)).
MATHEMATICA
a[1] = 0; a[n_] := a[n] = (n - 1)! (1 - Sum[d (a[d]/d!)^(n/d), {d, Divisors[n]~Complement~{1, n}}]); Table[a[n], {n, 1, 23}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, May 22 2022
STATUS
approved