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 A207713 #7 Jul 22 2025 20:42:34 %S A207713 10,100,450,2205,11970,66946,383845,2221688,12947130,75691595, %T A207713 443447550,2600917830,15265923595,89639239300,526483671750, %U A207713 3092701866155,18169057652502,106746028836790,627171773700111,3684942718387344 %N A207713 Number of nX4 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 0 vertically. %C A207713 Column 4 of A207717 %H A207713 R. H. Hardin, <a href="/A207713/b207713.txt">Table of n, a(n) for n = 1..210</a> %F A207713 Empirical: a(n) = 8*a(n-1) +6*a(n-2) -138*a(n-3) +52*a(n-4) +850*a(n-5) -487*a(n-6) -2284*a(n-7) +1340*a(n-8) +2858*a(n-9) -1584*a(n-10) -1736*a(n-11) +885*a(n-12) +500*a(n-13) -238*a(n-14) -60*a(n-15) +28*a(n-16) +2*a(n-17) -a(n-18) for n>19 %e A207713 Some solutions for n=4 %e A207713 ..1..0..1..0....0..1..1..0....0..1..1..0....1..0..1..0....1..1..1..1 %e A207713 ..0..1..1..0....1..1..0..0....0..1..0..0....0..1..0..0....1..1..0..1 %e A207713 ..1..0..1..0....0..1..1..0....0..1..1..0....1..1..1..0....0..1..1..1 %e A207713 ..0..1..1..0....1..1..1..0....0..1..1..0....0..1..1..0....1..0..1..0 %K A207713 nonn %O A207713 1,1 %A A207713 _R. H. Hardin_ Feb 19 2012