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 A003776 #19 Dec 23 2023 13:49:00 %S A003776 3,54,1140,24360,521064,11146656,238452456,5101047216,109123156248, %T A003776 2334395822496,49938107061384,1068291209653392,22853211220567416, %U A003776 488882861126970624 %N A003776 Number of 2-factors in P_5 X P_2n. %D A003776 F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Ars Combin. 49 (1998), 129-154. %H A003776 F. Faase, <a href="http://www.iwriteiam.nl/Cpaper.zip">On the number of specific spanning subgraphs of the graphs G X P_n</a>, Preliminary version of paper that appeared in Ars Combin. 49 (1998), 129-154. %H A003776 F. Faase, <a href="http://www.iwriteiam.nl/counting.html">Counting Hamiltonian cycles in product graphs</a> %H A003776 F. Faase, <a href="http://www.iwriteiam.nl/Cresults.html">Results from the counting program</a> %F A003776 a(n) = 24a(n-1) - 57a(n-2) + 26a(n-3), n>3. %F A003776 G.f.: 3x(1-5x)(1-x)/((1-2x)(1-22x+13x^2)). [From _R. J. Mathar_, Dec 16 2008] %K A003776 nonn %O A003776 1,1 %A A003776 _Frans J. Faase_