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 A207181 #7 Jul 22 2025 20:05:19 %S A207181 81,6561,248525,9196215,368714705,14960137403,600838995529, %T A207181 24069606968809,965286091829121,38732271412245771,1553999307045885583, %U A207181 62342694966576014475,2501032004180975268881,100336844251838872157471 %N A207181 Number of nX7 0..1 arrays avoiding 0 0 0 horizontally and 0 1 0 vertically. %C A207181 Column 7 of A207182 %H A207181 R. H. Hardin, <a href="/A207181/b207181.txt">Table of n, a(n) for n = 1..210</a> %e A207181 Some solutions for n=4 %e A207181 ..0..1..0..0..1..1..1....1..0..1..1..0..1..0....1..0..1..1..1..0..0 %e A207181 ..0..0..1..1..1..0..1....1..0..1..0..1..1..0....0..1..0..1..1..0..1 %e A207181 ..1..1..1..1..0..1..1....0..1..0..0..1..0..1....0..1..1..1..0..1..1 %e A207181 ..1..1..1..0..0..1..1....0..1..0..1..0..1..1....0..0..1..1..1..1..1 %K A207181 nonn %O A207181 1,1 %A A207181 _R. H. Hardin_ Feb 15 2012