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 A208553 #7 Jul 22 2025 21:24:18 %S A208553 26,676,3354,16641,50052,150544,351140,819025,1634430,3261636,5853246, %T A208553 10504081,17449544,28987456,45403272,71115489,106340130,159012100, %U A208553 229010210,329821921,460490316,642926736,874503084,1189491121,1582286342 %N A208553 Number of nX6 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 0 1 1 vertically. %C A208553 Column 6 of A208555 %H A208553 R. H. Hardin, <a href="/A208553/b208553.txt">Table of n, a(n) for n = 1..210</a> %F A208553 Empirical: a(n) = 2*a(n-1) +6*a(n-2) -14*a(n-3) -14*a(n-4) +42*a(n-5) +14*a(n-6) -70*a(n-7) +70*a(n-9) -14*a(n-10) -42*a(n-11) +14*a(n-12) +14*a(n-13) -6*a(n-14) -2*a(n-15) +a(n-16) %e A208553 Some solutions for n=4 %e A208553 ..0..1..0..1..0..1....1..0..1..0..1..0....1..1..1..1..0..1....0..1..0..1..0..1 %e A208553 ..1..1..1..1..1..1....1..1..0..1..0..0....0..1..0..1..0..0....0..1..0..1..1..1 %e A208553 ..0..1..0..1..0..1....1..0..1..0..1..0....0..1..1..1..0..0....0..1..0..1..0..0 %e A208553 ..0..1..1..0..1..1....0..1..0..1..0..0....0..1..0..1..0..0....0..1..0..1..0..1 %K A208553 nonn %O A208553 1,1 %A A208553 _R. H. Hardin_ Feb 28 2012