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 A380367 #8 Jan 31 2025 17:22:07 %S A380367 1,1,1,1,1,1,1,1,2,2,1,1,2,3,3,1,1,2,4,8,8,1,1,2,4,9,14,14,1,1,2,4,10, %T A380367 21,43,42,1,1,2,4,10,22,52,81,81,1,1,2,4,10,23,61,131,272,262,1,1,2,4, %U A380367 10,23,62,142,345,538,538,1,1,2,4,10,23,63,153,420,915,1920,1828 %N A380367 Array read by antidiagonals: meandric numbers for a river crossing up to k parallel roads at n points, n >= 0, k >= 1. %C A380367 Illustrations of the initial terms for the case of two parallel roads can be found in A076876. %H A380367 Andrew Howroyd, <a href="/A380367/b380367.txt">Table of n, a(n) for n = 0..945</a> (first 43 antidiagonals) %F A380367 T(n,k) = T(n,n) for k > n. %e A380367 Array begins: %e A380367 =================================================== %e A380367 n\k | 1 2 3 4 5 6 7 8 9 ... %e A380367 ----+---------------------------------------------- %e A380367 0 | 1 1 1 1 1 1 1 1 1 ... %e A380367 1 | 1 1 1 1 1 1 1 1 1 ... %e A380367 2 | 1 2 2 2 2 2 2 2 2 ... %e A380367 3 | 2 3 4 4 4 4 4 4 4 ... %e A380367 4 | 3 8 9 10 10 10 10 10 10 ... %e A380367 5 | 8 14 21 22 23 23 23 23 23 ... %e A380367 6 | 14 43 52 61 62 63 63 63 63 ... %e A380367 7 | 42 81 131 142 153 154 155 155 155 ... %e A380367 8 | 81 272 345 420 433 446 447 448 448 ... %e A380367 9 | 262 538 915 1017 1120 1135 1150 1151 1152 ... %e A380367 ... %Y A380367 Columns 1..19 are A005316, A076876, A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592. %Y A380367 Main diagonal is A206432. %Y A380367 Cf. A076875 (perpendicular roads). %K A380367 nonn,tabl %O A380367 0,9 %A A380367 _Andrew Howroyd_, Jan 31 2025