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A364761
G.f. satisfies A(x) = 1 / (1 + x*(1 + x*A(x))^3).
3
1, -1, -2, 5, 12, -41, -89, 391, 733, -4051, -6320, 44120, 54990, -496406, -465932, 5710408, 3637847, -66714699, -22683218, 787957397, 35371351, -9376925921, 2356626520, 112147043475, -61910867756, -1345231820826, 1158452138826, 16156200619772
OFFSET
0,3
FORMULA
a(n) = (1/(n+1)) * Sum_{k=0..n} (-1)^k * binomial(n+1,k) * binomial(3*k,n-k).
PROG
(PARI) a(n) = sum(k=0, n, (-1)^k*binomial(n+1, k)*binomial(3*k, n-k))/(n+1);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Aug 05 2023
STATUS
approved