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 A209227 #7 Jul 22 2025 21:41:17 %S A209227 19,361,456,576,1776,5476,15984,46656,143856,443556,1312020,3880900, %T A209227 11871220,36312676,108154648,322130704,980104384,2982033664, %U A209227 8920216800,26683222500,80907908400,245326052416,735864237328,2207251005124 %N A209227 Number of 6Xn 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 0 and 1 1 1 vertically. %C A209227 Row 6 of A209224 %H A209227 R. H. Hardin, <a href="/A209227/b209227.txt">Table of n, a(n) for n = 1..210</a> %F A209227 Empirical: a(n) = 2*a(n-1) +3*a(n-3) +71*a(n-4) -125*a(n-5) -25*a(n-6) -56*a(n-7) -1243*a(n-8) +2035*a(n-9) +168*a(n-10) +560*a(n-11) +6152*a(n-12) -9704*a(n-13) -848*a(n-14) -1472*a(n-15) -11056*a(n-16) +16688*a(n-17) +1472*a(n-18) +1536*a(n-19) +6976*a(n-20) -9536*a(n-21) -1024*a(n-22) -1024*a(n-24) +1024*a(n-25) for n>28 %e A209227 Some solutions for n=4 %e A209227 ..0..0..1..1....1..1..1..1....1..1..1..0....0..1..1..1....0..0..1..1 %e A209227 ..0..0..1..1....0..0..1..1....0..1..1..0....0..0..1..1....1..1..0..1 %e A209227 ..1..1..0..0....1..1..0..0....1..0..0..1....1..1..0..0....1..1..0..0 %e A209227 ..1..1..0..1....1..1..0..1....1..1..1..1....1..1..1..1....0..0..1..1 %e A209227 ..0..0..1..1....0..0..1..1....0..1..1..0....0..0..1..1....1..1..1..1 %e A209227 ..0..1..1..0....0..1..1..0....1..0..0..1....1..1..0..0....1..1..0..0 %K A209227 nonn %O A209227 1,1 %A A209227 _R. H. Hardin_ Mar 06 2012