A376491 G.f. satisfies A(x) = 1 / (1 - x^4*A(x)^4 / (1 - x)).
1, 0, 0, 0, 1, 1, 1, 1, 6, 11, 16, 21, 61, 136, 246, 391, 856, 1926, 3886, 7021, 14146, 30606, 64276, 125561, 251147, 527752, 1115877, 2273557, 4611992, 9583058, 20198698, 41982193, 86481758, 179676908, 377608039, 791559669, 1649078139, 3441054929
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n\4, binomial(5*k, k)*binomial(n-3*k-1, n-4*k)/(4*k+1));
Formula
a(n) = Sum_{k=0..floor(n/4)} binomial(5*k,k) * binomial(n-3*k-1,n-4*k) / (4*k+1).