A368440 - OEIS

%I #10 Dec 25 2023 10:02:11

%S 1,7,103,2287,67687,2504047,111163303,5757411247,340788559207,

%T 22693176094447,1679047763217703,136654363293340207,

%U 12133120656211741927,1167034341869994747247,120886955198779063694503,13416476227330202250197167,1588276885073067052758303847

%N Expansion of e.g.f. exp(x) / (3 - 2*exp(3*x)).

%F a(n) = 1 + 2 * Sum_{k=1..n} 3^k * binomial(n,k) * a(n-k).

%o (PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=1+2*sum(j=1, i, 3^j*binomial(i, j)*v[i-j+1])); v;

%Y Cf. A151919, A368441, A368453.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Dec 24 2023