OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..222
EXAMPLE
a(2) = (1/2) * (binomial(1+1,1) - binomial(1+2,2) + binomial(1+3,3) - binomial(2+1,1) + binomial(2+2,2) - binomial(2+3,3) + binomial(3+1,1) - binomial(3+2,2) + binomial(3+3,3)) = 5.
PROG
(PARI) {a(n) = sum(i=n, 3*n, (-1)^i*i!*polcoef(sum(j=1, 3, x^j/j!)^n, i))/n!}
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, May 22 2019
STATUS
approved