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 A007171 M1296 #18 Jul 08 2025 17:02:32 %S A007171 1,2,4,16,89,579,3989,28630,210865,1584308,12091902,93483120, %T A007171 730503054,5760438853,45780146521,366304396662,2948412461685, %U A007171 23857049238752,193944769559906,1583294537879106,12974430494985262,106685110047676402 %N A007171 Number of Q-graphs with 2n edges. %D A007171 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A007171 R. C. Read, <a href="http://dx.doi.org/10.1007/BF02188172">On the enumeration of a class of plane multigraphs</a>, Aequat. Math. 31 (1986) no 1, 47-63. %F A007171 a(1) = 1, a(n) = A007170(n) + (A003169(n-1) + A007165(n-1)) / 2. - _Sean A. Irvine_, Nov 07 2017 %Y A007171 Cf. A003169, A007165, A007170. %K A007171 nonn %O A007171 1,2 %A A007171 _N. J. A. Sloane_ %E A007171 a(9) corrected and more terms from _Sean A. Irvine_, Nov 07 2017