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 A005638 M1656 #53 Feb 16 2025 08:32:29 %S A005638 1,0,1,2,6,21,94,540,4207,42110,516344,7373924,118573592,2103205738, %T A005638 40634185402,847871397424,18987149095005,454032821688754, %U A005638 11544329612485981,310964453836198311,8845303172513781271 %N A005638 Number of unlabeled trivalent (or cubic) graphs with 2n nodes. %C A005638 Because the triangle A051031 is symmetric, a(n) is also the number of (2n-4)-regular graphs on 2n vertices. %D A005638 R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998. %D A005638 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A005638 G. Brinkmann, <a href="http://dx.doi.org/10.1002/(SICI)1097-0118(199610)23:2<139::AID-JGT5>3.0.CO;2-U">Fast generation of cubic graphs</a>, Journal of Graph Theory, 23(2):139-149, 1996. %H A005638 Jason Kimberley, <a href="/wiki/User:Jason_Kimberley/A051031">Not-necessarily connected regular graphs</a> %H A005638 Jason Kimberley, <a href="/wiki/User:Jason_Kimberley/E_k-reg_girth_ge_g_index">Index of sequences counting not necessarily connected k-regular simple graphs with girth at least g</a> %H A005638 R. W. Robinson, <a href="/A005636/a005636.pdf">Cubic graphs (notes)</a> %H A005638 Robinson, R. W.; Wormald, N. C., <a href="http://dx.doi.org/10.1002/jgt.3190070412">Numbers of cubic graphs</a>, J. Graph Theory 7 (1983), no. 4, 463-467. %H A005638 Peter Steinbach, <a href="/A000088/a000088_17.pdf">Field Guide to Simple Graphs, Volume 1</a>, Part 17 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.) %H A005638 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CubicGraph.html">Cubic Graph</a> %H A005638 Gal Weitz, Lirandë Pira, Chris Ferrie, and Joshua Combes, <a href="https://arxiv.org/abs/2308.14981">Sub-universal variational circuits for combinatorial optimization problems</a>, arXiv:2308.14981 [quant-ph], 2023. %F A005638 a(n) = A002851(n) + A165653(n). %F A005638 This sequence is the Euler transformation of A002851. %Y A005638 Cf. A000421. %Y A005638 Row sums of A275744. %Y A005638 3-regular simple graphs: A002851 (connected), A165653 (disconnected), this sequence (not necessarily connected). %Y A005638 Regular graphs A005176 (any degree), A051031 (triangular array), chosen degrees: A000012 (k=0), A059841 (k=1), A008483 (k=2), this sequence (k=3), A033301 (k=4), A165626 (k=5), A165627 (k=6), A165628 (k=7), A180260 (k=8). %Y A005638 Not necessarily connected 3-regular simple graphs with girth *at least* g: this sequence (g=3), A185334 (g=4), A185335 (g=5), A185336 (g=6). %Y A005638 Not necessarily connected 3-regular simple graphs with girth *exactly* g: A185133 (g=3), A185134 (g=4), A185135 (g=5), A185136 (g=6). %K A005638 nonn,nice %O A005638 0,4 %A A005638 _N. J. A. Sloane_ %E A005638 More terms from Ronald C. Read. %E A005638 Comment, formulas, and (most) crossrefs by _Jason Kimberley_, 2009 and 2012