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 A208144 #7 Jul 22 2025 21:11:42 %S A208144 10,100,450,2025,6300,19600,49000,122500,264600,571536,1111320, %T A208144 2160900,3880800,6969600,11761200,19847025,31853250,51122500,78728650, %U A208144 121242121,180360180,268304400,387550800,559795600,788351200,1110222400,1529388000 %N A208144 Number of 5Xn 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically. %C A208144 Row 5 of A208142 %H A208144 R. H. Hardin, <a href="/A208144/b208144.txt">Table of n, a(n) for n = 1..210</a> %F A208144 Empirical: a(n) = 2*a(n-1) +8*a(n-2) -18*a(n-3) -27*a(n-4) +72*a(n-5) +48*a(n-6) -168*a(n-7) -42*a(n-8) +252*a(n-9) -252*a(n-11) +42*a(n-12) +168*a(n-13) -48*a(n-14) -72*a(n-15) +27*a(n-16) +18*a(n-17) -8*a(n-18) -2*a(n-19) +a(n-20) %e A208144 Some solutions for n=4 %e A208144 ..0..0..0..0....0..0..0..0....0..0..0..0....1..0..1..0....0..1..0..0 %e A208144 ..1..0..0..0....1..1..0..0....0..1..0..1....1..1..1..1....0..0..0..0 %e A208144 ..0..0..0..0....0..0..0..0....0..0..0..0....0..1..0..1....0..0..0..0 %e A208144 ..0..0..0..0....0..0..0..0....0..0..0..0....0..1..0..0....0..0..0..0 %e A208144 ..0..0..0..0....0..0..0..0....0..0..0..0....0..1..0..0....0..0..0..0 %K A208144 nonn %O A208144 1,1 %A A208144 _R. H. Hardin_ Feb 23 2012