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 A362894 #27 Jun 18 2025 23:17:59
%S A362894 1,0,1,0,1,1,0,2,3,1,0,3,12,5,1,0,6,50,47,8,1,0,11,230,448,152,11,1
%N A362894 Triangle read by rows: T(n,k) is the number of simple connected graphs on n unlabeled nodes having Hadwiger number k, 1 <= k <= n.
%C A362894 All planar graphs have Hadwiger number <= 4. The converse is not true since planar graphs also disallow a minor of K_{3,3}. - _Andrew Howroyd_, Jun 18 2025
%H A362894 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HadwigerNumber.html">Hadwiger Number</a>
%H A362894 Wikipedia, <a href="https://en.wikipedia.org/wiki/Hadwiger_number">Hadwiger number</a>
%e A362894 Triangle begins:
%e A362894 1;
%e A362894 0, 1;
%e A362894 0, 1, 1;
%e A362894 0, 2, 3, 1;
%e A362894 0, 3, 12, 5, 1;
%e A362894 0, 6, 50, 47, 8, 1;
%e A362894 0, 11, 230, 448, 152, 11, 1;
%Y A362894 Row sums are A001349.
%Y A362894 Column 2 is A000055 for n > 1.
%Y A362894 Subdiagonal is A024206.
%Y A362894 Cf. A084269.
%Y A362894 Cf. A032766 (n-cocktail party graph). A353212 (n-path complement graph).
%K A362894 nonn,tabl,hard,more
%O A362894 1,8
%A A362894 _Peter Kagey_, May 08 2023