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 A006819 M4204 #14 Jul 08 2025 16:56:13 %S A006819 1,6,30,150,750,3726,18438,90966,447918,2201622,10809006,52999446, %T A006819 259668942,1271054982,6218232414,30399142614 %N A006819 Trails of length n on cubic lattice. %D A006819 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006819 A. J. Guttmann, <a href="http://dx.doi.org/10.1088/0305-4470/18/4/009">Lattice trails II: numerical results</a>, J. Phys. A 22 (1989), 575-588. %K A006819 nonn,walk %O A006819 0,2 %A A006819 _N. J. A. Sloane_