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 A221684 #6 Jun 02 2025 08:22:13 %S A221684 16,40,68,100,133,166,199,232,265,298,331,364,397,430,463,496,529,562, %T A221684 595,628,661,694,727,760,793,826,859,892,925,958,991,1024,1057,1090, %U A221684 1123,1156,1189,1222,1255,1288,1321,1354,1387,1420,1453,1486,1519,1552,1585 %N A221684 Number of 0..n arrays of length 5 with each element differing from at least one neighbor by 1 or less, starting with 0. %C A221684 Row 5 of A221683 %H A221684 R. H. Hardin, <a href="/A221684/b221684.txt">Table of n, a(n) for n = 1..210</a> %F A221684 Empirical: a(n) = 33*n - 32 for n>3 %e A221684 Some solutions for n=6 %e A221684 ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0 %e A221684 ..1....1....1....0....0....1....1....1....1....1....1....1....1....0....0....0 %e A221684 ..2....2....0....1....5....2....4....2....0....6....1....6....2....1....2....5 %e A221684 ..5....4....1....5....5....2....4....4....0....6....2....6....1....2....1....6 %e A221684 ..6....5....1....4....6....1....4....4....1....5....1....6....2....1....0....6 %K A221684 nonn %O A221684 1,1 %A A221684 _R. H. Hardin_ Jan 22 2013