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 A188689 #7 Jul 22 2025 11:18:09 %S A188689 7,49,218,857,3609,15942,69852,302053,1305379,5658937,24549216, %T A188689 106431608,461300682,1999592300,8668312567,37577096221,162893110032, %U A188689 706125302623,3060997024742,13269191906269,57520894059888,249348416142040 %N A188689 Number of nX3 binary arrays without the pattern 0 1 0 diagonally, vertically, antidiagonally or horizontally. %C A188689 Column 3 of A188695 %H A188689 R. H. Hardin, <a href="/A188689/b188689.txt">Table of n, a(n) for n = 1..200</a> %F A188689 Empirical: a(n) = 5*a(n-1) -8*a(n-2) +21*a(n-3) +9*a(n-4) -23*a(n-5) +45*a(n-6) -57*a(n-7) -112*a(n-8) +55*a(n-9) +93*a(n-10) -3*a(n-11) -27*a(n-12) -4*a(n-13) -6*a(n-14) %e A188689 Some solutions for 4X3 %e A188689 ..0..1..1....1..0..1....1..1..0....1..0..1....1..0..0....1..0..0....0..0..1 %e A188689 ..0..0..1....1..1..1....1..0..1....1..0..0....1..0..1....1..0..0....1..0..1 %e A188689 ..0..0..1....1..1..1....0..1..1....0..0..0....1..0..1....1..0..0....1..0..1 %e A188689 ..1..0..1....0..0..0....1..1..1....1..0..0....1..0..0....0..1..1....0..0..0 %K A188689 nonn %O A188689 1,1 %A A188689 _R. H. Hardin_ Apr 08 2011