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 A307072 #21 Apr 28 2019 17:35:35
%S A307072 0,0,0,0,1,11,149,3008,71335,1814021
%N A307072 Number of simple connected graphs on n nodes with crossing number 1.
%e A307072 5-node: K_5.
%e A307072 6-node: includes K_{1,2,3}, (5-1)-lollipop, 2 X 3 queen, utility graph K_{3,3}.
%Y A307072 Cf. A307071 (not necessarily connected graphs).
%Y A307072 Cf. A003094 (connected graphs with crossing number 0).
%K A307072 nonn,more
%O A307072 1,6
%A A307072 _Eric W. Weisstein_, Mar 22 2019
%E A307072 a(9) from _Eric W. Weisstein_, Apr 17 2019
%E A307072 a(10) from _Eric W. Weisstein_, Apr 28 2019