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 A203541 #7 Jun 02 2025 07:36:28 %S A203541 0,676,69920,8479744,1680210240,257720706244,44312000955508, %T A203541 7260263864381124,1226995111990493792,204147560099024833600, %U A203541 34127708705716358062368,5703975087798515553780804 %N A203541 Number of nX7 0..2 arrays with every element neighboring horizontally or vertically both a 0 and a 1. %C A203541 Column 7 of A203542 %H A203541 R. H. Hardin, <a href="/A203541/b203541.txt">Table of n, a(n) for n = 1..16</a> %e A203541 Some solutions for n=5 %e A203541 ..1..0..1..2..1..0..1....0..0..2..0..1..0..0....1..1..0..0..2..1..1 %e A203541 ..1..0..1..0..1..0..1....1..1..1..0..1..2..1....0..0..0..1..2..0..0 %e A203541 ..0..2..2..0..2..1..2....2..0..1..0..0..2..1....1..2..2..1..2..1..0 %e A203541 ..0..1..2..1..1..1..0....1..0..0..0..0..2..0....1..1..1..0..0..1..1 %e A203541 ..1..1..0..0..0..1..0....1..0..2..1..1..1..0....0..0..0..1..1..0..0 %K A203541 nonn %O A203541 1,2 %A A203541 _R. H. Hardin_ Jan 02 2012