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 A021103 #28 Jun 07 2023 09:40:56 %S A021103 0,0,0,1,3,9,44,294,2893,36496,545808,9029737,159563559,2952794985, %T A021103 56589742050 %N A021103 Number of two-connected (or biconnected) planar graphs with n nodes. %C A021103 For n < 3, conventions vary: Read & Wilson set a(2) = 0, but Gagarin et al. set a(2) = 1. - _Andrey Zabolotskiy_, Jun 07 2023 %D A021103 R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998. See p. 229. %H A021103 A. Gagarin, G. Labelle, P. Leroux, and T. Walsh, <a href="https://doi.org/10.1016/j.aam.2009.01.002">Structure and enumeration of two-connected graphs with prescribed three-connected components</a>, Adv. in Appl. Math. 43 (2009), no. 1, pp. 46-74. See (116) on p. 69. %Y A021103 Row sums of A049336. %Y A021103 The labeled version is A096331. %Y A021103 Cf. A000944 (3-connected), A002218, A003094, A005470. %K A021103 nonn,more %O A021103 0,5 %A A021103 _Brendan McKay_ %E A021103 a(12)-a(14) from Gilbert Labelle (labelle.gilbert(AT)uqam.ca), Jan 20 2009 %E A021103 Offset 0 from _Michel Marcus_, Jun 05 2023 %E A021103 a(2) changed back to 0 by _Georg Grasegger_ and _Andrey Zabolotskiy_, Jun 07 2023