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 A052113 #8 Sep 16 2018 16:51:17
%S A052113 1,5,41,1023,67173,10771355,5957216417,6971880064072,
%T A052113 32181855124938673,290910256437910060602,11266525980714327353251353,
%U A052113 815201852317091835592374861144,266236010885685869904935495261864265,157899403462038839125137738939159318226008
%N A052113 Number of self-complementary directed 2-multigraphs with loops on n nodes.
%C A052113 A 2-multigraph is similar to an ordinary graph except there are 0, 1 or 2 edges between any two nodes (self-loops are not allowed).
%D A052113 V. Jovovic, On the number of m-place relations (in Russian), Logiko-algebraicheskie konstruktsii, Tver, 1992, 59-66.
%H A052113 Andrew Howroyd, <a href="/A052113/b052113.txt">Table of n, a(n) for n = 1..50</a>
%o A052113 (PARI)
%o A052113 permcount(v) = {my(m=1,s=0,k=0,t); for(i=1,#v,t=v[i]; k=if(i>1&&t==v[i-1],k+1,1); m*=t*k;s+=t); s!/m}
%o A052113 edges(v) = {2*sum(i=2, #v, sum(j=1, i-1, if(v[i]*v[j]%2==0, gcd(v[i],v[j])))) + sum(i=1, #v, if(v[i]%2==0, v[i]))}
%o A052113 a(n) = {my(s=0); forpart(p=n, s+=permcount(p)*3^edges(p)); s/n!} \\ _Andrew Howroyd_, Sep 16 2018
%Y A052113 Cf. A004105, A047832.
%K A052113 nonn
%O A052113 1,2
%A A052113 _Vladeta Jovovic_, Jan 21 2000
%E A052113 Terms a(14) and beyond from _Andrew Howroyd_, Sep 16 2018