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 A350910 #8 Jan 29 2022 20:13:46 %S A350910 1,1,1,1,1,1,1,2,2,1,1,2,5,2,1,1,4,23,23,4,1,1,4,92,415,92,4,1,1,7, %T A350910 624,19041,19041,624,7,1,1,8,5021,1104045,6510087,1104045,5021,8,1,1, %U A350910 12,47034,79818336,2983458766,2983458766,79818336,47034,12,1 %N A350910 Triangle read by rows: T(n,k) is the number of k-regular digraphs on n unlabeled nodes, k = 0..n-1. %e A350910 Triangle begins: %e A350910 1; %e A350910 1, 1; %e A350910 1, 1, 1; %e A350910 1, 2, 2, 1; %e A350910 1, 2, 5, 2, 1; %e A350910 1, 4, 23, 23, 4, 1; %e A350910 1, 4, 92, 415, 92, 4, 1; %e A350910 1, 7, 624, 19041, 19041, 624, 7, 1; %e A350910 ... %Y A350910 Columns k=0..6 are A000012, A002865, A219889, A219890, A219891, A219892, A219893. %Y A350910 Row sums are A350911. %Y A350910 Cf. A051031 (graphs), A329228 (semi-regular), A350912. %K A350910 nonn,tabl %O A350910 1,8 %A A350910 _Andrew Howroyd_, Jan 29 2022