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 A189336 #7 Jul 22 2025 11:42:37 %S A189336 4,16,64,225,784,2704,9409,32761,114244,398161,1387684,4835601, %T A189336 16851025,58721569,204633025,713103616,2485022500,8659791364, %U A189336 30177596089,105162706944,366470415424,1277074025929,4450340433889,15508521343396 %N A189336 Number of nX2 binary arrays without the pattern 1 0 0 1 diagonally, vertically, antidiagonally or horizontally. %C A189336 Column 2 of A189343 %H A189336 R. H. Hardin, <a href="/A189336/b189336.txt">Table of n, a(n) for n = 1..200</a> %F A189336 Empirical: a(n) = 4*a(n-1) -a(n-2) -6*a(n-3) +12*a(n-4) -3*a(n-5) +3*a(n-6) -6*a(n-7) +a(n-8) -a(n-9) +a(n-10) %e A189336 Some solutions for 4X2 %e A189336 ..0..0....1..0....1..0....0..0....1..0....0..1....0..0....0..1....1..1....0..0 %e A189336 ..1..1....1..0....0..0....1..0....1..0....0..1....1..1....1..0....0..1....1..1 %e A189336 ..0..0....1..0....1..0....0..1....0..1....0..1....1..0....0..1....1..0....1..1 %e A189336 ..0..1....0..1....1..1....0..1....1..1....0..0....0..1....1..0....0..1....1..1 %Y A189336 A049864(n+2) squared %K A189336 nonn %O A189336 1,1 %A A189336 _R. H. Hardin_ Apr 20 2011