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 A208453 #21 Dec 06 2015 11:45:36 %S A208453 1,1,2,4,10,23,63,155,447,1150,3433,9118,27923,75981,237379,658380, %T A208453 2090519,5888530,18951534,54069881,176020213,507632647,1668910009, %U A208453 4857449082,16106998656,47253245257,157874165288,466367068388,1568587476660,4661900731148,15773729508730 %N A208453 Meandric numbers for a river crossing up to 7 parallel roads at n points. %C A208453 Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 7 parallel East-West roads n times. %C A208453 Sequence derived from list of solutions described in A206432. %H A208453 Andrew Howroyd, <a href="/A208453/b208453.txt">Table of n, a(n) for n = 0..36</a> %Y A208453 Cf. A005316 (sequence for one road; extensive references and links). %Y A208453 Cf. A076876 (sequence for two parallel roads). %Y A208453 Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads). %Y A208453 Cf. A206432 (sequence for unlimited number of parallel roads). %Y A208453 Cf. A076875, A076906, A076907. %K A208453 nonn %O A208453 0,3 %A A208453 _Robert Price_, May 07 2012 %E A208453 a(21)-a(36) from _Andrew Howroyd_, Dec 05 2015