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 A005194 M1017 #21 Oct 28 2023 09:33:16
%S A005194 1,2,4,6,10,22,38,102,182,574,1070,3798,7286,28894,57374,248502,
%T A005194 506678,2384254,5007230,25247958,54311126,292500574,645652574,
%U A005194 3680048502,8301671798,49967727934,115334270270,728281984278,1714641313046,11341092707614
%N A005194 Number of balanced symmetric graphs.
%D A005194 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A005194 David A. Sheppard, <a href="http://dx.doi.org/10.1016/0012-365X(76)90051-0">The factorial representation of balanced labelled graphs</a>, Discrete Math. 15 (1976), no. 4, 379-388.
%F A005194 Let S(n,j) = j! * j^floor((n-2)/2). If n is even, then a(n) = 2 * Sum_{j=1..n/2} S(n,j). If n is odd, and (n-1)/2 is odd, then a(n) = ((n+1)/2)! + 2 * Sum_{j=1,3,5,...,(n-1)/2} S(n, j). Otherwise, n is odd, and (n-1)/2 is even, then a(n) = ((n+1)/2)! + ((n-1)/2)! + 2 * Sum_{j=1,3,5,...,(n-1)/2-1} S(n, j) [From Sheppard paper]. - _Sean A. Irvine_, Apr 18 2016
%K A005194 nonn
%O A005194 1,2
%A A005194 _N. J. A. Sloane_
%E A005194 More terms from _Sean A. Irvine_, Apr 18 2016