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 A001184 #19 Jan 30 2022 12:31:25 %S A001184 1,2,104,111712,2688307514,1445778936756068,17337631013706758184626, %T A001184 4628650743368437273677525554148, %U A001184 27478778338807945303765092195103685118924 %N A001184 Number of simple Hamiltonian paths connecting opposite corners of a 2n+1 X 2n+1 grid. %F A001184 a(n) = A121788(2n), n>0. - _Ashutosh Mehra_, Dec 19 2008 %Y A001184 Cf. A121788, A333580. %K A001184 nonn,more,walk %O A001184 0,2 %A A001184 _Don Knuth_, Dec 07 1995 %E A001184 a(7)-a(8) copied from A121788 by _Alois P. Heinz_, Sep 27 2014