A370605 a(n) = n! * Sum_{d|n} 1/((d-1)! * (n/d)!^d).
1, 3, 4, 11, 6, 72, 8, 499, 850, 4988, 12, 142232, 14, 949392, 7385394, 26739587, 18, 1462302432, 20, 21233776156, 253684768502, 151243121780, 24, 104533367794192, 25973364296906, 102776106948752, 26798029481115778, 95394359150584904, 30
Offset: 1
Keywords
Crossrefs
Cf. A370581.
Programs
-
PARI
a(n) = n!*sumdiv(n, d, 1/((d-1)!*(n/d)!^d));
-
PARI
my(N=30, x='x+O('x^N)); Vec(serlaplace(sum(k=1, N, x^k/k!*exp(x^k/k!))))
Formula
If p is prime, a(p) = 1 + p.
E.g.f.: Sum_{k>0} x^k/k! * exp(x^k/k!).