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 A375050 #13 Aug 02 2024 19:00:32
%S A375050 0,1,18,576,29400,2205225,228953088,31473598464,5537223659520,
%T A375050 1213834310015625,324468643299372000,103900389446258786304,
%U A375050 39267840204934404964992,17296280109081832136303025,8783270052027947513856000000,5094007565002120817604034560000
%N A375050 Obverse convolution (n(n+1)/2)**(n(n+1)/2); see Comments.
%C A375050 See A374848 for the definition of obverse convolution and a guide to related sequences. a(2k+1) is a square for k>=0.
%F A375050 a(n) ~ n^(2*n+2) / (2^(n+1) * exp(2*n - Pi*(n+1)/2)). - _Vaclav Kotesovec_, Jul 31 2024
%F A375050 a(n) = (n*(n+1)/2) * [1-(n+s)/2]_n * [1-(n-s)/2]_n, where s = sqrt(-n*(2 + n)) and [x]_n is the Pochhammer function. - _Peter Luschny_, Aug 02 2024
%p A375050 t:= n-> n*(n+1)/2:
%p A375050 a:= n-> mul(t(n-j)+t(j), j=0..n):
%p A375050 seq(a(n), n=0..15); # _Alois P. Heinz_, Aug 02 2024
%t A375050 s[n_] := n (n + 1)/2;
%t A375050 u[n_] := Product[s[k] + s[n - k], {k, 0, n}];
%t A375050 Table[u[n], {n, 0, 20}]
%Y A375050 Cf. A000217, A374848.
%K A375050 nonn
%O A375050 0,3
%A A375050 _Clark Kimberling_, Jul 31 2024