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 A188501 #11 Feb 18 2018 08:33:16 %S A188501 4,16,49,144,441,1369,4225,12996,40000,123201,379456,1168561,3598609, %T A188501 11082241,34128964,105103504,323676081,996791184,3069714025, %U A188501 9453478441,29112890625,89655929476,276104007936,850288696321,2618545348864 %N A188501 Number of n X 2 binary arrays without the pattern 0 1 0 diagonally, vertically or horizontally. %C A188501 Column 2 of A188508. %H A188501 R. H. Hardin, <a href="/A188501/b188501.txt">Table of n, a(n) for n = 1..200</a> %F A188501 Empirical: a(n)=3*a(n-1)-a(n-2)+3*a(n-3)+3*a(n-4)-a(n-5)-a(n-6). %F A188501 Empirical g.f.: x*(4 + 4*x + 5*x^2 + x^3 - 2*x^4 - x^5) / ((1 - x + 2*x^2 - x^3)*(1 - 2*x - 3*x^2 - x^3)). - _Colin Barker_, Feb 18 2018 %e A188501 Some solutions for 3 X 2: %e A188501 ..1..1....0..1....1..1....1..1....0..1....1..0....0..1....1..1....1..1....0..1 %e A188501 ..1..0....1..0....1..1....0..0....0..1....1..0....0..0....0..1....0..1....0..0 %e A188501 ..1..0....1..0....1..0....1..0....1..1....0..1....1..1....1..1....1..0....1..0 %K A188501 nonn %O A188501 1,1 %A A188501 _R. H. Hardin_, Apr 02 2011