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 A361405 #8 Mar 11 2023 19:46:27 %S A361405 1,2,28,1408,580656,2658827456,146702084635392,98485306566812364032, %T A361405 820443196111261227164076544,86804253216450161933010414314819072, %U A361405 119212631345634236227720012129209606659383296,2166023316743980619769969171366251471253351621687457792 %N A361405 Number of graphs with loops on 2n unlabeled vertices with n loops. %C A361405 a(n) is the number of bicolored graphs on 2n unlabeled nodes with an equal number of each color. Adjacent vertices may have the same color. %H A361405 Andrew Howroyd, <a href="/A361405/b361405.txt">Table of n, a(n) for n = 0..25</a> %F A361405 a(n) = A361404(2*n, n). %o A361405 (PARI) a(n) = row(2*n)[n+1] \\ row(n) defined in A361404. %Y A361405 Central coefficients of A361404. %Y A361405 Cf. A007139. %K A361405 nonn %O A361405 0,2 %A A361405 _Andrew Howroyd_, Mar 11 2023