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 A062031 #17 Jun 09 2025 12:13:08
%S A062031 1,105,328185,5568833025,304513870485825,40992233865440682825,
%T A062031 11492457771692770753505625,5984524775454356180393209490625,
%U A062031 5325142910343897163530366857379506625,7598549164899334249502031499667984969915625
%N A062031 Group odd numbers into (1), (3,5,7), (9,11,13,15,17), ...; a(n) = product of n-th group.
%H A062031 Harry J. Smith, <a href="/A062031/b062031.txt">Table of n, a(n) for n=1..100</a>
%F A062031 a(n) = Product_{k=0..2*n-2} (2*k + 2*n*(n-2) + 3). - _Harry J. Smith_, Jul 30 2009
%F A062031 a(n) = (Gamma(2*n^2 + 1)*Gamma((n-1)^2 + 1))/(2^(2*n-1)*Gamma(n^2 + 1)*Gamma(2*(n-1)^2 + 1)). - _G. C. Greubel_, May 06 2022
%F A062031 a(n) ~ exp(-2) * 2^(2*n-1) * n^(4*n-2). - _Vaclav Kotesovec_, Jun 09 2025
%e A062031 a(2) = 3*5*7 = 105.
%t A062031 Table[(Gamma[2*n^2 +1]*Gamma[(n-1)^2 +1])/(2^(2*n-1)*Gamma[n^2 +1]*Gamma[2*(n-1)^2 +1]), {n, 30}] (* _G. C. Greubel_, May 06 2022 *)
%o A062031 (PARI) a(n) = { my(b=2*n^2 - 4*n + 3); prod(k=0, 2*n - 2, b + 2*k) } \\ _Harry J. Smith_, Jul 30 2009
%o A062031 (SageMath) [(gamma(2*n^2 +1)*gamma((n-1)^2 +1))/(2^(2*n-1)*gamma(n^2 +1)*gamma(2*(n-1)^2 +1)) for n in (1..30)] # _G. C. Greubel_, May 06 2022
%Y A062031 Cf. A062029, A062030, A062032.
%K A062031 nonn
%O A062031 1,2
%A A062031 _Amarnath Murthy_, Jun 02 2001
%E A062031 More terms from _Matthew Conroy_, Jun 11 2001