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 A209622 #20 Jan 31 2025 17:43:02 %S A209622 1,1,2,4,10,23,63,155,448,1152,3452,9157,28176,76514,240318,664718, %T A209622 2122557,5959052,19289899,54828151,179538447,515641437,1705240090, %U A209622 4941294887,16481424379,48127922888,161736798007,475487875843,1608541737898,4757151493126,16188528696215 %N A209622 Meandric numbers for a river crossing up to 10 parallel roads at n points. %C A209622 Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 10 parallel East-West roads n times. %C A209622 Sequence derived from list of solutions described in A206432. %H A209622 Andrew Howroyd, <a href="/A209622/b209622.txt">Table of n, a(n) for n = 0..36</a> %Y A209622 Column k=10 of A380367. %Y A209622 Cf. A005316 (sequence for one road; extensive references and links). %Y A209622 Cf. A076876 (sequence for two parallel roads). %Y A209622 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 A209622 Cf. A206432 (sequence for unlimited number of parallel roads). %Y A209622 Cf. A076875, A076906, A076907. %K A209622 nonn %O A209622 0,3 %A A209622 _Robert Price_, May 07 2012 %E A209622 a(21)-a(36) from _Andrew Howroyd_, Dec 06 2015