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A364737
G.f. satisfies A(x) = 1 + x*A(x) / (1 + x*A(x)^4).
4
1, 1, 0, -4, -6, 28, 119, -116, -1820, -2128, 22212, 79877, -172700, -1652728, -857428, 25387284, 71506309, -268817888, -1838702048, 449975584, 33164610276, 68575577309, -429542625096, -2221814345660, 2539462697398, 46048818685880, 61721413191310
OFFSET
0,4
FORMULA
a(n) = (1/n) * Sum_{k=0..n-1} (-1)^k * binomial(n,k) * binomial(n+3*k,n-1-k) for n > 0.
PROG
(PARI) a(n) = if(n==0, 1, sum(k=0, n-1, (-1)^k*binomial(n, k)*binomial(n+3*k, n-1-k))/n);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Aug 05 2023
STATUS
approved