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A324403 a(n) = Product_{i=1..n, j=1..n} (i^2 + j^2). 16
2, 400, 121680000, 281324160000000000, 15539794609114833408000000000000, 49933566483104048708063697937367040000000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Next term is too long to be included.

LINKS

Table of n, a(n) for n=1..6.

FORMULA

a(n) ~ 2^(n*(n+1) - 3/4) * exp(Pi*n*(n+1)/2 - 3*n^2 + Pi/12) * n^(2*n^2 - 1/2) / (Pi^(1/4) * Gamma(3/4)).

a(n) = 2*n^2*a(n-1)*Product_{i=1..n-1} (n^2 + i^2)^2. - Chai Wah Wu, Feb 26 2019

MATHEMATICA

Table[Product[i^2+j^2, {i, 1, n}, {j, 1, n}], {n, 1, 10}]

PROG

(PARI) a(n) = prod(i=1, n, prod(j=1, n, i^2+j^2)); \\ Michel Marcus, Feb 27 2019

CROSSREFS

Cf. A079478, A293290, A324402, A324443, A324426, A324437, A324438, A324439, A324440.

Sequence in context: A249177 A249178 A281650 * A214597 A283661 A067827

Adjacent sequences:  A324400 A324401 A324402 * A324404 A324405 A324406

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Feb 26 2019

STATUS

approved

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Last modified December 6 01:46 EST 2021. Contains 349558 sequences. (Running on oeis4.)