This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A324442 #14 Dec 28 2023 03:01:14 %S A324442 1,2,180,6652800,402265543680000,109211487076824381849600000, %T A324442 295382703175843424854047228769075200000000, %U A324442 15385012566245626089929288743828190926813939944652800000000000 %N A324442 a(n) = Product_{i=1..n, j=1..n} (i^2 + j). %F A324442 From _Vaclav Kotesovec_, Dec 27 2023: (Start) %F A324442 a(n) ~ c * n^(2*n^2 + n/2 - 1/4) / exp(2*n^2 - 2*Pi*n^(3/2)/3 - Pi*sqrt(n)/2), where c = 0.31906... %F A324442 For n>1, a(n) = a(n-1) * Gamma(n - i*sqrt(n)) * Gamma(n + i*sqrt(n)) * Gamma(n^2 + n + 1) * sinh(Pi*sqrt(n)) / (Pi * n^(5/2) * Gamma(n^2)), where i is the imaginary unit. (End) %p A324442 a:= n-> mul(mul(i^2+j, i=1..n), j=1..n): %p A324442 seq(a(n), n=0..8); # _Alois P. Heinz_, Jun 24 2023 %t A324442 Table[Product[i^2 + j, {i, 1, n}, {j, 1, n}], {n, 1, 10}] %t A324442 Table[Product[Pochhammer[1 + i^2, n], {i, 1, n}], {n, 1, 10}] %Y A324442 Cf. A079478, A101686, A255322, A324403. %K A324442 nonn %O A324442 0,2 %A A324442 _Vaclav Kotesovec_, Feb 28 2019 %E A324442 a(0)=1 prepended by _Alois P. Heinz_, Jun 24 2023