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 A077551 #12 Aug 14 2012 15:50:27 %S A077551 0,1,3,5,16,31,105,218,770,1673,6096,13672,51027,117194,445787, %T A077551 1042970,4028922,9567393,37432324,89984282,355854272 %N A077551 Meandric numbers for a river (or directed line) crossing two perpendicular roads at n points, beginning in the (-,-) quadrant, crossing x axis first and ending in any quadrant. %Y A077551 Similar to A076907 but must cross x axis first. %K A077551 nonn,more %O A077551 0,3 %A A077551 _N. J. A. Sloane_ and _Jon Wild_, Aug 25 2003 %E A077551 a(7) corrected by _Robert Price_, Jul 29 2012 %E A077551 a(8)-a(20) from _Robert Price_, Aug 14 2012