OFFSET
0,3
COMMENTS
a(n) = 0 when n is a multiple of 4 (A008586). - Michel Marcus, Apr 11 2018
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..398
MAPLE
seq(Im(mul(k+(n-k+1)*I, k=1..n)), n=0..30); # Muniru A Asiru, Apr 11 2018
PROG
(PARI) {a(n) = imag(prod(k=1, n, k+(n-k+1)*I))}
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Apr 11 2018
STATUS
approved