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 A006663 M0374 #30 Jun 28 2017 15:17:37 %S A006663 1,1,2,2,8,12,52,86,400,710,3404,6316,30888,59204,293192,576018, %T A006663 2877184,5764430,28967428,58970568,297634344,614037754,3109111064 %N A006663 Number of projective meanders. %D A006663 S. K. Lando and A. K. Zvonkin, "Plane and projective meanders", Séries Formelles et Combinatoire Algébrique. Laboratoire Bordelais de Recherche Informatique, Université Bordeaux I, 1991, pp. 287-303. %D A006663 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006663 S. K. Lando and A. K. Zvonkin , <a href="/A005316/a005316_1.pdf">Plane and projective meanders</a>, Séries Formelles et Combinatoire Algébrique. Laboratoire Bordelais de Recherche Informatique, Université Bordeaux I, 1991, pp. 287-303. (Annotated scanned copy) %H A006663 S. K. Lando and A. K. Zvonkin, <a href="http://dx.doi.org/10.1016/0304-3975(93)90316-L">Plane and projective meanders</a>, Theoretical Computer Science Vol. 117 (1993), no. 1-2, 227-241. %K A006663 nonn,nice,more %O A006663 0,3 %A A006663 _N. J. A. Sloane_, _Simon Plouffe_ %E A006663 a(16)-a(22) from _Andrew Howroyd_, Mar 30 2017