A307066 a(n) = exp(-1) * Sum_{k>=0} (n*k + 1)^n/k!.

1, 2, 13, 199, 5329, 216151, 12211597, 909102342, 85761187393, 9957171535975, 1390946372509101, 229587693339867567, 44117901231194922193, 9748599124579281064294, 2451233017637221706477037, 695088863051920283838281851, 220558203335628758134165860609

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..250

Formula

a(n) = n! * [x^n] exp(exp(n*x) + x - 1).

a(n) = Sum_{k=0..n} binomial(n,k) * n^k * Bell(k).

Mathematica

Table[Exp[-1] Sum[(n k + 1)^n/k!, {k, 0, Infinity}], {n, 0, 16}]
Table[n! SeriesCoefficient[Exp[Exp[n x] + x - 1], {x, 0, n}], {n, 0, 16}]
Join[{1}, Table[Sum[Binomial[n, k] n^k BellB[k], {k, 0, n}], {n, 1, 16}]]

Prog

(Magma)
A307066:= func< n | (&+[Binomial(n, k)*n^k*Bell(k): k in [0..n]]) >;
[A307066(n): n in [0..31]]; // G. C. Greubel, Jan 24 2024
(SageMath)
def A307066(n): return sum(binomial(n, k)*n^k*bell_number(k) for k in range(n+1))
[A307066(n) for n in range(31)] # G. C. Greubel, Jan 24 2024

Crossrefs

Cf. A000110, A126390, A134980, A284859, A285064, A292914, A307080.

Sequence in context: A049512 A003507 A338979 * A361368 A003085 A053598

Adjacent sequences: A307063 A307064 A307065 * A307067 A307068 A307069

Keyword

nonn

Author

Ilya Gutkovskiy, Jun 24 2019

Status

approved