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 A206993 #7 Jul 22 2025 19:54:22 %S A206993 81,6561,80070,2371090,60684900,1482397764,37849652838,954576893140, %T A206993 24031904480250,606711286710758,15303296459686032,385968153194641688, %U A206993 9736392679516458222,245594233526815556440,6194918451958959626262 %N A206993 Number of nX7 0..1 arrays avoiding 0 0 0 horizontally and 1 1 1 vertically. %C A206993 Column 7 of A206994 %H A206993 R. H. Hardin, <a href="/A206993/b206993.txt">Table of n, a(n) for n = 1..210</a> %e A206993 Some solutions for n=4 %e A206993 ..0..0..1..1..1..0..0....0..1..1..1..0..1..0....1..0..1..0..1..0..0 %e A206993 ..1..0..0..1..1..0..1....1..0..0..1..1..1..0....1..1..0..0..1..1..1 %e A206993 ..0..0..1..0..0..1..0....0..1..0..0..1..0..1....0..1..0..1..0..1..1 %e A206993 ..1..1..0..0..1..1..0....0..0..1..1..0..1..0....0..0..1..1..1..0..0 %K A206993 nonn %O A206993 1,1 %A A206993 _R. H. Hardin_ Feb 14 2012