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Expansion of e.g.f. exp( Sum_{k>=0} x^(3*k+2) / (3*k+2)! ).
2

%I #67 Sep 22 2023 11:32:03

%S 1,0,1,0,3,1,15,21,106,378,1116,6931,20196,136500,558559,3103191,

%T 18524418,90852217,661904622,3569749659,25657118047,171935108541,

%U 1149965503347,9166884110308,62758177512570,525194926694256,4072360499426311,33295056117878646

%N Expansion of e.g.f. exp( Sum_{k>=0} x^(3*k+2) / (3*k+2)! ).

%F a(0)=1; a(n) = Sum_{k=0..floor((n-2)/3)} binomial(n-1,3*k+1) * a(n-3*k-2).

%o (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=0, N\3, x^(3*k+2)/(3*k+2)!))))

%Y Cf. A000296, A365419.

%K nonn

%O 0,5

%A _Seiichi Manyama_, Sep 22 2023