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 A006433 M3720 #17 Apr 06 2021 21:13:05 %S A006433 0,4,175,3324,42469,429120,3711027,28723640,204598130,1366223880, %T A006433 8664086470,52673351080,309164754285,1761471681568,9783594370723, %U A006433 53154274959360,283267669144390,1484104565936920,7658877239935362,38993558097982312,196127054929939810 %N A006433 Number of tree-rooted planar maps with 4 vertices and n faces and no isthmuses. %C A006433 A map without isthmuses can also be called bridgeless. %D A006433 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006433 Andrew Howroyd, <a href="/A006433/b006433.txt">Table of n, a(n) for n = 1..100</a> %H A006433 T. R. S. Walsh and A. B. Lehman, <a href="http://dx.doi.org/10.1016/0095-8956(75)90050-7">Counting rooted maps by genus. III: Nonseparable maps</a>, J. Combinatorial Theory Ser. B 18 (1975), 222-259. See Table VIIIb. %Y A006433 A diagonal of A342987. %K A006433 nonn %O A006433 1,2 %A A006433 _N. J. A. Sloane_ %E A006433 Terms a(12) and beyond from _Andrew Howroyd_, Apr 06 2021