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 A217318 #29 Nov 25 2018 12:57:55 %S A217318 0,0,0,1,10,20,156,273,1986,3358,23742,39736,277178,462794,3205896, %T A217318 5355743,36963722,61856394,426075994,714515312,4916833424,8263479072, %U A217318 56840484232,95733461792,658460090994,1111253958664,7644360501390,12925362323004,88938175307354 %N A217318 The number of meandering curves of order n, with both extremity covered by its arcs. %C A217318 A meandering curve of order n is a continuous curve which does not intersect itself yet intersects a horizontal line n times. %D A217318 A. Panayotopoulos and P. Tsikouras, Properties of meanders, JCMCC 46 (2003), 181-190. %H A217318 Panayotis Vlamos, <a href="/A217318/b217318.txt">Table of n, a(n) for n = 1..42</a> %H A217318 A. Panayotopoulos, P. Vlamos, <a href="http://dx.doi.org/10.1007/s11786-015-0234-0">Partitioning the Meandering Curves</a>, Mathematics in Computer Science (2015) p 1-10. %F A217318 a(n) = A223095(n) * A000034(n) / 2. - _Andrew Howroyd_, Dec 06 2015 %Y A217318 Cf. A005315. %K A217318 nonn %O A217318 1,5 %A A217318 _Panayotis Vlamos_, _Antonios Panayotopoulos_, and Georgia Theocharopoulou, Mar 18 2013