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 A208500 #7 Jul 22 2025 21:24:04 %S A208500 42,1764,1728,5436,13806,37430,111328,286754,844200,2336928,6407688, %T A208500 18684540,50681028,145645192,408090270,1135228896,3261392100, %U A208500 8999952300,25648313760,72191962584,201563085152,574718422958,1602200548928 %N A208500 Number of nX7 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 0 and 1 1 1 vertically. %C A208500 Column 7 of A208501 %H A208500 R. H. Hardin, <a href="/A208500/b208500.txt">Table of n, a(n) for n = 1..210</a> %e A208500 Some solutions for n=4 %e A208500 ..0..1..1..1..1..1..1....0..1..1..1..0..1..1....1..0..1..0..1..1..0 %e A208500 ..1..0..1..0..1..0..1....0..1..0..1..0..1..0....0..1..1..0..1..0..1 %e A208500 ..1..1..0..1..0..1..0....1..0..1..0..1..0..1....0..1..0..1..0..1..1 %e A208500 ..0..1..0..1..1..1..1....1..1..1..1..1..1..1....1..0..1..1..1..1..0 %K A208500 nonn %O A208500 1,1 %A A208500 _R. H. Hardin_ Feb 27 2012