A370696 - OEIS

%I #6 Feb 27 2024 09:47:59

%S 1,1,2,12,48,240,1800,12600,100800,967680,9676800,106444800,

%T 1297296000,16864848000,236107872000,3552515366400,56840245862400,

%U 966284179660800,17402007419596800,330638140972339200,6612762819446784000,138878156300083200000

%N Expansion of e.g.f. exp(x^3)/(1-x).

%F a(n) = n! * Sum_{k=0..floor(n/3)} 1/k!.

%o (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x^3)/(1-x)))

%o (PARI) a(n) = n!*sum(k=0, n\3, 1/k!);

%Y Cf. A000522, A355268.

%Y Cf. A130906.

%K nonn,easy

%O 0,3

%A _Seiichi Manyama_, Feb 27 2024