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A302661 Real part of Product_{k=1..n} (k+(n-k+1)i), with i=sqrt(-1). 3
1, 1, 0, -20, -221, -1560, 0, 272000, 6356025, 84086080, 0, -40560998400, -1449723503125, -28152429760000, 0, 26582971351040000, 1279483892211136625, 32774236110420480000, 0, -51128938217766256640000, -3094745459011904478178125, -98456230888859903488000000, 0, 229377281607595274010624000000 (list; graph; refs; listen; history; text; internal format)
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

Cf. A016825, A301616.

Imaginary part: A302662.

Sequence in context: A140354 A155673 A000833 * A178261 A054329 A112503

Adjacent sequences: A302658 A302659 A302660 * A302662 A302663 A302664

KEYWORD

sign

AUTHOR

Seiichi Manyama, Apr 11 2018

STATUS

approved

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Last modified November 27 00:20 EST 2022. Contains 358362 sequences. (Running on oeis4.)