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 A140636 #21 Jun 22 2025 13:43:22 %S A140636 0,0,0,2,13,93,809,11005,260793,11715808,1006698524,164059824899, %T A140636 50335907853919,29003487462805642,31397381142761123838, %U A140636 63969560113225175845492,245871831682084026518599099,1787331725248899088890197955308,24636021429399867655322650752269938 %N A140636 Number of connected graphs on n unlabeled nodes that contain at least two cycles. %C A140636 Original name: number of unlabeled complex components with n nodes. %C A140636 We can find in "The Birth of the Giant Component", p. 2, see the first link: %C A140636 "As each of the random graphs evolved, the story went, never once was there more than a single 'complex' component; i.e. there never were two or more components present simultaneously that were neither trees nor unicyclic." %C A140636 So a complex component is a connected graph that is neither a tree nor an unicyclic graph. %H A140636 Andrew Howroyd, <a href="/A140636/b140636.txt">Table of n, a(n) for n = 1..50</a> %H A140636 Svante Janson, Donald E. Knuth, Tomasz Łuczak and Boris Pittel, <a href="http://www.math.uu.se/~svante/papers/index.html">The Birth of the Giant Component</a>, <a href="http://dx.doi.org/ 10.1002/rsa.3240040303">[DOI]</a>, Rand. Struct. Alg. 4 (3) (1993) 233-358 %H A140636 N. J. A. Sloane, <a href="/A000088/a000088.gif">Illustration of initial terms of A001349</a>. %F A140636 a(n) = A001349(n) - A005703(n). %F A140636 a(n) = A001349(n) - A000055(n) - A001429(n). %e A140636 a(4) = 2. See the two complex components with 4 nodes in the Sloane illustration. %Y A140636 The labeled version is A140638. %Y A140636 Cf. A001349, A000055, A001429, A005703. %K A140636 nonn %O A140636 1,4 %A A140636 _Washington Bomfim_, May 20 2008 %E A140636 Name changed by _Andrew Howroyd_, Jan 16 2022