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 A077556 #6 Mar 31 2012 10:32:24 %S A077556 0,1,2,5,12,31,81,239 %N A077556 Meandric numbers for an undirected line crossing two perpendicular roads at n points, beginning in the (-,-) quadrant, crossing x axis first and ending in any quadrant. %Y A077556 Similar to A077551 but line is undirected. %K A077556 nonn,more %O A077556 0,3 %A A077556 _N. J. A. Sloane_ and _Jon Wild_, Aug 25 2003