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 A188561 #7 Jul 22 2025 11:15:50 %S A188561 7,49,247,1383,7722,42712,237116,1315783,7300042,40505756,224748056, %T A188561 1247024929,6919195733,38391539384,213017628693,1181940415631, %U A188561 6558063227535,36387785244039,201899687047572,1120251845376251 %N A188561 Number of nX3 binary arrays without the pattern 1 1 1 diagonally, vertically or horizontally. %C A188561 Column 3 of A188567 %H A188561 R. H. Hardin, <a href="/A188561/b188561.txt">Table of n, a(n) for n = 1..200</a> %F A188561 Empirical: a(n)=a(n-1)+11*a(n-2)+60*a(n-3)+89*a(n-4)+107*a(n-5)-75*a(n-6)-50*a(n-7)-157*a(n-8)+184*a(n-9)-91*a(n-10)+86*a(n-11)-35*a(n-12)+13*a(n-13)-14*a(n-14)+4*a(n-15) %e A188561 Some solutions for 4X3 %e A188561 ..0..0..0....0..1..0....0..0..0....0..0..0....0..0..0....0..1..1....1..0..0 %e A188561 ..0..1..0....0..1..0....0..1..1....1..1..0....1..1..0....1..1..0....0..1..1 %e A188561 ..1..1..0....1..0..1....1..0..1....0..0..1....0..1..1....0..0..1....1..1..0 %e A188561 ..0..0..1....0..0..1....0..0..0....1..1..0....1..0..0....0..0..1....1..0..1 %K A188561 nonn %O A188561 1,1 %A A188561 _R. H. Hardin_ Apr 04 2011