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 A123545 #7 Nov 22 2020 20:22:36 %S A123545 0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0, %T A123545 2,4,5,4,2,1,1,0,0,0,0,0,0,0,0,0,0,0,4,18,30,34,29,17,9,5,2,1,1,0,0,0, %U A123545 0,0,0,0,0,0,0,0,0,5,35,136,309,465,505,438,310,188,103,52,23 %N A123545 Triangle read by rows: T(n,k) = number of unlabeled connected graphs on n nodes with degree >= 3 at each node (n >= 1, 0 <= k <= n(n-1)/2). %D A123545 R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1978. %H A123545 R. W. Robinson, <a href="/A123545/b123545.txt">Rows 1 through 14, flattened</a> %e A123545 Triangle begins: %e A123545 n = 1 %e A123545 k = 0 : 0 %e A123545 ************************ TOTAL (n = 1) = 0 %e A123545 n = 2 %e A123545 k = 0 : 0 %e A123545 k = 1 : 0 %e A123545 ************************ TOTAL (n = 2) = 0 %e A123545 n = 3 %e A123545 k = 0 : 0 %e A123545 k = 1 : 0 %e A123545 k = 2 : 0 %e A123545 k = 3 : 0 %e A123545 ************************ TOTAL (n = 3) = 0 %e A123545 n = 4 %e A123545 k = 0 : 0 %e A123545 k = 1 : 0 %e A123545 k = 2 : 0 %e A123545 k = 3 : 0 %e A123545 k = 4 : 0 %e A123545 k = 5 : 0 %e A123545 k = 6 : 1 %e A123545 ************************ TOTAL (n = 4) = 1 %e A123545 n = 5 %e A123545 k = 0 : 0 %e A123545 k = 1 : 0 %e A123545 k = 2 : 0 %e A123545 k = 3 : 0 %e A123545 k = 4 : 0 %e A123545 k = 5 : 0 %e A123545 k = 6 : 0 %e A123545 k = 7 : 0 %e A123545 k = 8 : 1 %e A123545 k = 9 : 1 %e A123545 k = 10 : 1 %e A123545 ************************ TOTAL (n = 5) = 3 %e A123545 From _Hugo Pfoertner_, Nov 22 2020: (Start) %e A123545 Transposed table: %e A123545 Nodes Sums %e A123545 4 5 6 7 8 9 10 11 12 13 |A338604 %e A123545 Edges-----------------------------------------------------|------- %e A123545 6 | 1 . . . . . . . . . | 1 %e A123545 7 | . . . . . . . . . . | 0 %e A123545 8 | . 1 . . . . . . . . | 1 %e A123545 9 | . 1 2 . . . . . . . | 3 %e A123545 10 | . 1 4 . . . . . . . | 5 %e A123545 11 | . . 5 4 . . . . . . | 9 %e A123545 12 | . . 4 18 5 . . . . . | 27 %e A123545 13 | . . 2 30 35 . . . . . | 67 %e A123545 14 | . . 1 34 136 27 . . . . | 198 %e A123545 15 | . . 1 29 309 288 19 . . . | 646 %e A123545 16 | . . . 17 465 1377 357 . . . | 2216 %e A123545 17 | . . . 9 505 3978 3478 208 . . | 8178 %e A123545 18 | . . . 5 438 7956 18653 4958 85 . | 32085 %e A123545 19 | . . . 2 310 11904 65011 50575 4291 . | 132093 %e A123545 20 | . . . 1 188 14134 163812 302854 85421 1958 | 568368 %e A123545 (End) %Y A123545 Row sums give A007112. Cf. A123546, A338604. %K A123545 nonn,tabf %O A123545 1,35 %A A123545 _N. J. A. Sloane_, Nov 13 2006