A364627 G.f. satisfies A(x) = 1/(1-x)^3 + x^2*A(x)^4.
1, 3, 7, 22, 97, 469, 2339, 12148, 65295, 358979, 2006977, 11380702, 65311575, 378574425, 2213092750, 13032826536, 77244242937, 460413902079, 2758088752351, 16596379614234, 100269075879881, 607996092039949, 3698873710967989, 22570809986322440
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n\2, binomial(n+7*k+2, 9*k+2)*binomial(4*k, k)/(3*k+1));
Formula
a(n) = Sum_{k=0..floor(n/2)} binomial(n+7*k+2,9*k+2) * binomial(4*k,k) / (3*k+1).