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 A324740 #14 Feb 16 2025 08:33:58 %S A324740 0,0,2,4,8,15,25,41,65,100,150,225,327,474,678,962,1348,1884,2602, %T A324740 3581,4889,6644,8968,12064,16124,21476,28462,37585,49407,64747,84495, %U A324740 109936,142522,184226,237350,304977,390669,499169,636039,808468,1024996,1296573,1636151 %N A324740 Number of simple graphs on n unlabeled nodes with maximum degree exactly 2. %H A324740 Andrew Howroyd, <a href="/A324740/b324740.txt">Table of n, a(n) for n = 1..1000</a> %H A324740 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MaximumVertexDegree.html">Maximum Vertex Degree</a> %F A324740 a(n) = A003292(n) - A008619(n). %o A324740 (PARI) seq(n) = Vec( (1-x)*(1-x^2)/prod(k=1, n, 1 - x^k + O(x*x^n))^2 - 1/((1-x)*(1-x^2)), -n) \\ _Andrew Howroyd_, Sep 03 2019 %Y A324740 Column k=2 of A263293. %Y A324740 A diagonal of A294217. %Y A324740 Cf. A003292, A008619. %K A324740 nonn %O A324740 1,3 %A A324740 _Andrew Howroyd_, Sep 03 2019