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 A207894 #7 Jul 22 2025 20:56:54 %S A207894 28,784,2520,20168,135714,856480,5888458,39828558,260749390, %T A207894 1761010222,11829617422,78462173820,526979351782,3530615876490, %U A207894 23530243300772,157698231146356,1055466664497864,7048335728590736,47191056299318688 %N A207894 Number of nX7 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 0 and 1 1 1 vertically. %C A207894 Column 7 of A207895 %H A207894 R. H. Hardin, <a href="/A207894/b207894.txt">Table of n, a(n) for n = 1..210</a> %e A207894 Some solutions for n=4 %e A207894 ..0..1..0..0..1..1..1....1..0..0..1..1..1..0....0..0..1..1..1..1..0 %e A207894 ..0..1..1..1..0..0..1....0..1..0..0..1..0..0....0..1..0..0..1..0..0 %e A207894 ..1..0..0..1..1..0..0....0..1..1..1..0..0..1....1..1..1..0..0..1..1 %e A207894 ..0..1..0..0..1..1..0....1..0..0..1..1..1..1....0..0..1..1..0..0..1 %K A207894 nonn %O A207894 1,1 %A A207894 _R. H. Hardin_ Feb 21 2012