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A302662 Imaginary part of Product_{k=1..n} (k+(n-k+1)i), with i=sqrt(-1). 3
0, 1, 5, 20, 0, -1560, -26825, -272000, 0, 84086080, 2484885325, 40560998400, 0, -28152429760000, -1180588763732625, -26582971351040000, 0, 32774236110420480000, 1780605230870046303125, 51128938217766256640000, 0, -98456230888859903488000000, -6569779608356896665959265625 (list; graph; refs; listen; history; text; internal format)
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

Cf. A008586, A301616.

Real part: A302661.

Sequence in context: A013531 A122152 A104314 * A261545 A093482 A283522

Adjacent sequences:  A302659 A302660 A302661 * A302663 A302664 A302665

KEYWORD

sign

AUTHOR

Seiichi Manyama, Apr 11 2018

STATUS

approved

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Last modified September 21 00:17 EDT 2019. Contains 327252 sequences. (Running on oeis4.)