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A369480
Expansion of (1/x) * Series_Reversion( x / ((1+x)^2 * (1+x+x^2)^3) ).
3
1, 5, 38, 342, 3379, 35427, 387038, 4358119, 50222276, 589439699, 7021368716, 84669873678, 1031603223880, 12679812357672, 157038146685360, 1957792379658934, 24549963008189965, 309435808369427643, 3918185776941808956, 49818464846052855850, 635788103792527271239
OFFSET
0,2
FORMULA
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(3*n+3,k) * binomial(5*n-k+5,n-2*k).
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^2*(1+x+x^2)^3))/x)
(PARI) a(n, s=2, t=3, u=2) = sum(k=0, n\s, binomial(t*(n+1), k)*binomial((t+u)*(n+1)-k, n-s*k))/(n+1);
CROSSREFS
Sequence in context: A316598 A228657 A370476 * A365839 A113207 A158266
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jan 23 2024
STATUS
approved