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A366082
Expansion of (1/x) * Series_Reversion( x*(1-x)^3/(1-x-x^2) ).
3
1, 2, 6, 21, 79, 308, 1219, 4826, 18857, 71574, 257553, 837114, 2140496, 1379550, -35589730, -370646635, -2719034151, -17429175486, -103771133876, -588804389677, -3225403649859, -17180039158530, -89342552789741, -454604059204324, -2265246385921936
OFFSET
0,2
LINKS
FORMULA
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} (-1)^k * binomial(n+1,k) * binomial(3*n-k+1,n-2*k).
PROG
(PARI) a(n) = sum(k=0, n\2, (-1)^k*binomial(n+1, k)*binomial(3*n-k+1, n-2*k))/(n+1);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Sep 28 2023
STATUS
approved