A294120 E.g.f.: exp(3*((1+x)^3 - 1)).

1, 9, 99, 1233, 16929, 251829, 4012011, 67876461, 1211592897, 22700600001, 444567396051, 9068604811209, 192115381719969, 4216003141209453, 95631348748295259, 2237799925576748709, 53928909429116324481, 1336410276724468307961

Offset: 0

Author

Seiichi Manyama, Oct 23 2017

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..511

Crossrefs

Column k=3 of A294118.

Programs

Mathematica

nmax = 20; CoefficientList[Series[E^(3*((1+x)^3 - 1)), {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Oct 23 2017 *)

PARI

N=66; x='x+O('x^N); Vec(serlaplace(exp(3*((1+x)^3-1))))

Formula

a(n) ~ 3^(2*n/3 - 1/2) * n^(2*n/3) * exp(-2 + 3^(1/3)*n^(1/3) + 3^(2/3)*n^(2/3) - 2*n/3). - Vaclav Kotesovec, Oct 23 2017