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A361847
a(n) = (-1)^n * Sum_{k=0..n} 9^k * binomial(-1/3,k) * binomial(n*k,n-k).
3
1, 3, 12, 27, -75, -444, 4734, 11532, -466782, 1626750, 50347410, -708889296, -2196754992, 179878246239, -1795732735128, -24691325878980, 953903679982809, -7684914725016600, -226465559200630566, 7742131606464606525, -58889021552013912990
OFFSET
0,2
LINKS
FORMULA
a(n) = [x^n] 1/(1 - 9*x*(1-x)^n)^(1/3).
PROG
(PARI) a(n) = (-1)^n*sum(k=0, n, 9^k*binomial(-1/3, k)*binomial(n*k, n-k));
CROSSREFS
Main diagonal of A361840.
Sequence in context: A058034 A294416 A187273 * A009259 A183503 A216713
KEYWORD
sign
AUTHOR
Seiichi Manyama, Mar 27 2023
STATUS
approved