OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = [x^n] Product_{k=1..n} (1 - n*x^k).
PROG
(PARI) {a(n) = polcoeff(prod(k=1, n, 1-n*x^k+x*O(x^n)), n)}
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Sep 09 2017
STATUS
approved