

A302661


Real part of Product_{k=1..n} (k+(nk+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
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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+(nk+1)*I, k=1..n)), n=0..30); # Muniru A Asiru, Apr 11 2018


PROG

(PARI) {a(n) = real(prod(k=1, n, k+(nk+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



