A302661 - OEIS

A302661

Real part of Product_{k=1..n} (k+(n-k+1)i), with i=sqrt(-1).

1, 1, 0, -20, -221, -1560, 0, 272000, 6356025, 84086080, 0, -40560998400, -1449723503125, -28152429760000, 0, 26582971351040000, 1279483892211136625, 32774236110420480000, 0, -51128938217766256640000, -3094745459011904478178125, -98456230888859903488000000, 0, 229377281607595274010624000000

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OFFSET

0,4

COMMENTS

a(n) = 0 for n mod 4 = 2 (A016825). - Michel Marcus, Apr 11 2018

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..398

MAPLE

seq(Re(mul(k+(n-k+1)*I, k=1..n)), n=0..30); # Muniru A Asiru, Apr 11 2018

PROG

(PARI) {a(n) = real(prod(k=1, n, k+(n-k+1)*I))}

CROSSREFS