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 A232042 #7 Oct 02 2018 06:31:54 %S A232042 4,15,80,446,2477,13752,76375,424115,2355221,13079032,72630752, %T A232042 403334385,2239803950,12438120321,69071597937,383569664377, %U A232042 2130046094920,11828611039210,65686859759121,364773474308192,2025666747456127 %N A232042 Number of n X 3 0..1 arrays with no element less than a strict majority of its horizontal and antidiagonal neighbors. %H A232042 R. H. Hardin, <a href="/A232042/b232042.txt">Table of n, a(n) for n = 1..210</a> %F A232042 Empirical: a(n) = 4*a(n-1) + 9*a(n-2) -a (n-3) - 6*a(n-4) for n>5. %F A232042 Empirical g.f.: x*(4 - x - 16*x^2 - 5*x^3 + 12*x^4) / (1 - 4*x - 9*x^2 + x^3 + 6*x^4). - _Colin Barker_, Oct 02 2018 %e A232042 Some solutions for n=7: %e A232042 ..1..1..0....1..1..0....0..0..1....1..1..0....1..0..0....1..1..1....1..1..0 %e A232042 ..0..0..0....1..0..0....0..1..0....0..0..0....0..0..0....1..0..0....0..0..0 %e A232042 ..1..1..0....1..1..1....1..0..0....0..1..0....0..0..0....0..1..0....0..0..0 %e A232042 ..1..0..1....0..0..0....1..0..0....0..0..0....1..0..1....0..0..0....0..0..0 %e A232042 ..0..1..0....0..0..0....0..1..0....1..1..1....0..1..1....1..0..0....1..1..1 %e A232042 ..0..0..0....1..0..1....0..0..0....0..0..0....0..0..0....1..1..1....0..0..1 %e A232042 ..0..0..0....0..1..1....0..0..1....1..0..0....0..0..0....0..0..0....0..1..1 %Y A232042 Column 3 of A232047. %K A232042 nonn %O A232042 1,1 %A A232042 _R. H. Hardin_, Nov 17 2013