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 A165655 #26 Feb 16 2025 08:33:11 %S A165655 0,0,0,0,0,0,1,3,66,8029,3484760,2595985770,2815099031417, %T A165655 4230059694039460,8529853839173455678,22496718465713456081402, %U A165655 75951258300080722467845995,322269241532759484921710401976 %N A165655 Number of disconnected 5-regular (quintic) graphs on 2n vertices. %H A165655 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a> %H A165655 Jason Kimberley, <a href="/wiki/User:Jason_Kimberley/A068933">Disconnected regular graphs (with girth at least 3)</a> %H A165655 Jason Kimberley, <a href="/wiki/User:Jason_Kimberley/D_k-reg_girth_ge_g_index">Index of sequences counting disconnected k-regular simple graphs with girth at least g</a> %H A165655 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DisconnectedGraph.html">Disconnected Graph</a> %H A165655 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/QuinticGraph.html">Quintic Graph</a> %F A165655 a = A165626 - A006821 = Euler_transformation(A006821) - A006821. %F A165655 a(n)=A068933(2n,5). %Y A165655 5-regular simple graphs: A006821 (connected), this sequence (disconnected), A165626 (not necessarily connected). %Y A165655 Disconnected regular simple graphs: A068932 (any degree), A068933 (triangular array), specified degree k: A165652 (k=2), A165653 (k=3), A033483 (k=4), this sequence (k=5), A165656 (k=6), A165877 (k=7), A165878 (k=8), A185293 (k=9), A185203 (k=10), A185213 (k=11). %K A165655 nonn,hard,more %O A165655 0,8 %A A165655 _Jason Kimberley_, Sep 28 2009 %E A165655 Terms a(13)-a(17), due to the extension of A006821 by _Andrew Howroyd_, from _Jason Kimberley_, Mar 12 2020