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 A318793 #17 Dec 15 2018 07:26:47
%S A318793 1,0,10,84,12060,922680,203474180,45546045720,16977056982648,
%T A318793 7385901628225968,4359210462435545640,3063111491275816418020,
%U A318793 2669859570203387710219500,2738752987417403052110951664,3328615281192062743163487239944
%N A318793 Constant term in the expansion of (Sum_{k=0..n} k*(x^k + x^(-k)))^n.
%H A318793 Vaclav Kotesovec, <a href="/A318793/b318793.txt">Table of n, a(n) for n = 0..214</a>
%F A318793 a(n) ~ exp(1) * n^(2*n - 3/2) / sqrt(Pi). - _Vaclav Kotesovec_, Dec 15 2018
%e A318793 (2/x^2 + 1/x + 0 + x + 2*x^2)^2 = 4/x^4 + 4/x^3 + 1/x^2 + 4/x + 10 + 4*x + x^2 + 4*x^3 + 4*x^4. So a(2) = 10.
%t A318793 a[n_] := If[n==0, 1, Coefficient[Expand[Sum[k*(x^k + x^(-k)), {k, 0, n}]^n], x, 0]]; Array[a, 15, 0] (* _Amiram Eldar_, Dec 15 2018 *)
%o A318793 (PARI) {a(n) = polcoeff((sum(k=0, n, k*(x^k+x^(-k))))^n, 0, x)}
%Y A318793 Cf. A286928, A318794.
%K A318793 nonn
%O A318793 0,3
%A A318793 _Seiichi Manyama_, Dec 15 2018