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A368967
Expansion of (1/x) * Series_Reversion( x * (1-x)^2 * (1-x-x^2)^2 ).
8
1, 4, 28, 238, 2244, 22568, 237199, 2574276, 28627224, 324503718, 3735672880, 43555658640, 513277420803, 6103767231712, 73153216133600, 882708243017414, 10714917867247020, 130752597362068496, 1603069096165788706, 19737123968746454284, 243930175282166574432
OFFSET
0,2
FORMULA
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(2*n+k+1,k) * binomial(5*n-k+3,n-2*k).
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-x)^2*(1-x-x^2)^2)/x)
(PARI) a(n, s=2, t=2, u=2) = sum(k=0, n\s, binomial(t*(n+1)+k-1, k)*binomial((t+u+1)*(n+1)-(s-1)*k-2, n-s*k))/(n+1);
CROSSREFS
Cf. A368968.
Sequence in context: A151830 A354693 A112113 * A369510 A188266 A192625
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jan 10 2024
STATUS
approved