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 A210478 #20 Jan 31 2025 17:23:12 %S A210478 1,1,2,4,10,23,63,155,448,1152,3452,9158,28178,76539,240370,665129, %T A210478 2123439,5964691,19302315,54898415,179696520,516468865,1707135922, %U A210478 4950704681,16503326351,48232594797,161983781556,476635904628,1611283232139,4769631412013,16218646880868 %N A210478 Meandric numbers for a river crossing up to 17 parallel roads at n points. %C A210478 Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 17 parallel East-West roads n times. %C A210478 Sequence derived from list of solutions described in A206432. %H A210478 Andrew Howroyd, <a href="/A210478/b210478.txt">Table of n, a(n) for n = 0..40</a> %Y A210478 Column k=17 of A380367. %Y A210478 Cf. A005316 (sequence for one road; extensive references and links). %Y A210478 Cf. A076876 (sequence for two parallel roads). %Y A210478 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 A210478 Cf. A206432 (sequence for unlimited number of parallel roads). %Y A210478 Cf. A076875, A076906, A076907. %K A210478 nonn %O A210478 0,3 %A A210478 _Robert Price_, May 07 2012 %E A210478 a(21) onwards from _Andrew Howroyd_, Jan 31 2025