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 A307210 #16 Jun 24 2023 16:23:15 %S A307210 1,3,5100,305727048000,7748770873210669158912000, %T A307210 476007332700693200670745550306381336371200000, %U A307210 272661655519533773844144991586798737775635133552905539740860416000000000 %N A307210 a(n) = Product_{i=1..n, j=1..n} (i^3 + j^3 + 1). %C A307210 Product_{i=1..n, j=1..n} (1 + 1/(i + j)) = A324444(n) / A079478(n) ~ 2^(2*n + 1) / (sqrt(Pi)*n^(3/2)). %C A307210 Product_{i=1..n, j=1..n} (1 + 1/(i^2 + j^2)) = A324443(n) / A324403(n) ~ c * n^(Pi/2), where c = A306398 * 2^(3/4) * exp(-Pi/12) * Pi^(1/4) * Gamma(3/4) = 0.36753062884677326134620846786416595535234038999313315993144237973600... %F A307210 a(n) ~ A307209 * A324426(n). %F A307210 a(n) ~ c * A * 2^(2*n*(n+1) + 1/4) * exp(Pi*(n*(n+1) + 1/6)/sqrt(3) - 9*n^2/2 - 1/12) * n^(3*n^2 - 3/4) / (3^(5/6) * Pi^(1/6) * Gamma(2/3)^2), where c = A307209 = Product_{i>=1, j>=1} (1 + 1/(i^3 + j^3)) = 3.504782999339728375891120570... and A is the Glaisher-Kinkelin constant A074962. %p A307210 a:= n-> mul(mul(i^3+j^3+1, i=1..n), j=1..n): %p A307210 seq(a(n), n=0..7); # _Alois P. Heinz_, Jun 24 2023 %t A307210 Table[Product[i^3 + j^3 + 1, {i, 1, n}, {j, 1, n}], {n, 1, 8}] %Y A307210 Cf. A307209, A324403, A324426, A324443, A324444. %K A307210 nonn %O A307210 0,2 %A A307210 _Vaclav Kotesovec_, Mar 28 2019 %E A307210 a(0)=1 prepended by _Alois P. Heinz_, Jun 24 2023