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 A208117 #7 Jul 22 2025 21:10:40 %S A208117 40,1600,9240,53361,175560,577600,1432600,3553225,7419360,15492096, %T A208117 28791840,53509225,91408240,156150016,250232400,401000625,611163000, %U A208117 931470400,1363358920,1995498241,2824994040,3999297600,5505737640 %N A208117 Number of nX7 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 0 1 1 vertically. %C A208117 Column 7 of A208118 %H A208117 R. H. Hardin, <a href="/A208117/b208117.txt">Table of n, a(n) for n = 1..210</a> %F A208117 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 A208117 Some solutions for n=4 %e A208117 ..1..0..1..1..1..0..1....1..1..1..0..1..1..0....1..1..1..1..0..0..1 %e A208117 ..0..1..1..1..1..0..1....1..1..1..1..0..0..1....1..0..1..1..1..0..0 %e A208117 ..0..0..1..1..0..0..1....1..1..0..0..1..1..0....0..0..1..1..0..0..1 %e A208117 ..0..0..1..1..1..0..1....1..1..1..1..0..0..1....0..0..1..1..1..0..0 %K A208117 nonn %O A208117 1,1 %A A208117 _R. H. Hardin_ Feb 23 2012