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 A199654 #7 Jul 22 2025 13:22:13 %S A199654 365,571530,713445976,898852775335,1132589231853096, %T A199654 1427019666767669979,1797997097480559332224,2265416280260844187870380, %U A199654 2854348741463033805904551375,3596383952736036093799275624989 %N A199654 Number of nX7 0..2 arrays with values 0..2 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors. %C A199654 Column 7 of A199655 %H A199654 R. H. Hardin, <a href="/A199654/b199654.txt">Table of n, a(n) for n = 1..35</a> %e A199654 Some solutions for n=3 %e A199654 ..0..0..0..1..2..1..0....0..0..0..1..1..1..2....0..0..0..0..1..2..1 %e A199654 ..0..1..0..2..0..2..1....0..1..0..2..0..0..2....0..1..1..1..2..2..1 %e A199654 ..0..0..0..1..0..0..0....0..0..0..1..1..2..0....0..0..0..2..0..0..2 %K A199654 nonn %O A199654 1,1 %A A199654 _R. H. Hardin_ Nov 08 2011