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 A006648 M1181 #19 Jul 08 2025 16:51:26 %S A006648 1,1,2,4,9,20,50,124,332,895,2513,7172,20994,62366,188696,578717, %T A006648 1799999,5666257,18047319,58097540,188953756,620493315,2056582095, %U A006648 6877206111,23195975865,78891742748,270505303760,934890953041,3256230606767 %N A006648 Number of graphs with n nodes, n-1 edges and no isolated vertices. %D A006648 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 A006648 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %F A006648 a(n) = A001433(n) - A001434(n - 1). - _Sean A. Irvine_, Jun 06 2017 %Y A006648 Cf. A001433, A001434. %K A006648 nonn %O A006648 2,3 %A A006648 _N. J. A. Sloane_ %E A006648 More terms from _Vladeta Jovovic_, Mar 02 2008 %E A006648 More terms from _Sean A. Irvine_, Jun 06 2017