A348146 a(n) = Sum_{d|n} (d!)^(n-d).

1, 2, 2, 6, 2, 234, 2, 331842, 46658, 24883200258, 2, 139314179589392898, 2, 82606411253903523840004098, 619173642242176782338, 6984964247141514123665660725036072962, 2, 109110688415571335888754861121236891599318185050114, 2

Offset

1,2

Links

Seiichi Manyama, Table of n, a(n) for n = 1..61

Formula

a(p) = 2 for primes p.

G.f.: Sum_{k>=1} x^k/(1 - (k! * x)^k). - Seiichi Manyama, Oct 03 2021

Mathematica

Table[Sum[(i!)^(n - i) (1 - Ceiling[n/i] + Floor[n/i]), {i, n}], {n, 20}]

Prog

(PARI) a(n) = sumdiv(n, d, d!^(n-d)); \\ Seiichi Manyama, Oct 03 2021
(PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-(k!*x)^k))) \\ Seiichi Manyama, Oct 03 2021

Crossrefs

Cf. A062363, A342628, A345465, A346196.

Sequence in context: A230266 A342628 A329380 * A355076 A344007 A130478

Adjacent sequences: A348143 A348144 A348145 * A348147 A348148 A348149

Keyword

nonn

Author

Wesley Ivan Hurt, Oct 02 2021

Status

approved