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 A006649 M1474 #16 Jan 09 2024 16:24:08 %S A006649 1,0,0,1,2,5,15,41,124,369,1132,3491,10984,34768,111514,360560, %T A006649 1176797,3870389,12829765,42829894,143980892,487227611,1659499566, %U A006649 5688046485,19617965938,68078878268,237694501644,834946053269,2950683815028,10490767818951,37524169403930 %N A006649 Number of graphs with n nodes, n edges and no isolated vertices. %D A006649 W. L. Kocay, Some new methods in reconstruction theory, pp. 89 - 114 of Combinatorial Mathematics IX. Proc. Ninth Australian Conference (Brisbane, August 1981). Ed. E. J. Billington, S. Oates-Williams and A. P. Street. Lecture Notes Math., 952. Springer-Verlag, 1982. %D A006649 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006649 Andrew Howroyd, <a href="/A006649/b006649.txt">Table of n, a(n) for n = 0..50</a> %F A006649 a(n) = A008406(n,n) - A008406(n-1, n) for n > 0. - _Andrew Howroyd_, Jan 09 2024 %o A006649 (PARI) a(n) = polcoef(G(n, O(x*x^n)) - if(n, G(n-1, O(x*x^n))), n) \\ G defined in A008406. - _Andrew Howroyd_, Jan 09 2024 %Y A006649 Cf. A001434, A008406, A048179, A368599. %K A006649 nonn %O A006649 0,5 %A A006649 _N. J. A. Sloane_ %E A006649 More terms from _Vladeta Jovovic_, Mar 02 2008 %E A006649 a(0)-a(2) prepended and a(27) and beyond from _Andrew Howroyd_, Jan 09 2024