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 A360866 #6 Feb 25 2023 20:57:54 %S A360866 0,0,1,0,1,0,1,1,0,1,3,2,0,1,4,7,0,1,6,19,6,0,1,8,40,37,6,0,1,10,71, %T A360866 135,56,0,1,12,117,366,338,35,0,1,15,184,858,1417,494,20,0,1,17,270, %U A360866 1778,4670,3494,492,0,1,20,387,3413,13125,17355,6047,251 %N A360866 Triangle read by rows: T(n,k) is the number of unlabeled connected loopless multigraphs with n edges on k nodes and degree >= 3 at each node, n >= 2, 1 <= k <= floor(2*n/3). %C A360866 Terms may be computed using the tools geng, vcolg and multig in nauty with some additional processing to check the degrees of nodes. %H A360866 Brendan McKay and Adolfo Piperno, <a href="http://pallini.di.uniroma1.it/">nauty and Traces</a>. %e A360866 Triangle begins: %e A360866 0; %e A360866 0, 1; %e A360866 0, 1; %e A360866 0, 1, 1; %e A360866 0, 1, 3, 2; %e A360866 0, 1, 4, 7; %e A360866 0, 1, 6, 19, 6; %e A360866 0, 1, 8, 40, 37, 6; %e A360866 0, 1, 10, 71, 135, 56; %e A360866 0, 1, 12, 117, 366, 338, 35; %e A360866 0, 1, 15, 184, 858, 1417, 494, 20; %e A360866 0, 1, 17, 270, 1778, 4670, 3494, 492; %e A360866 0, 1, 20, 387, 3413, 13125, 17355, 6047, 251; %e A360866 ... %Y A360866 Row sums are A360867. %Y A360866 Diagonal sums are A360868. %Y A360866 Cf. A046752, A191646, A360862 (loops allowed). %K A360866 nonn,tabf %O A360866 2,11 %A A360866 _Andrew Howroyd_, Feb 24 2023