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 A183305 #7 Jul 22 2025 08:47:50 %S A183305 2,6,19,55,178,572,1798,5700,18064,57249,181433,574924,1821857, %T A183305 5773450,18295845,57978643,183731482,582236576,1845081304,5846978390, %U A183305 18528805856,58716935815,186071279593,589651361292,1868578146701,5921438527588 %N A183305 Half the number of nX4 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors. %C A183305 Column 4 of A183312 %H A183305 R. H. Hardin, <a href="/A183305/b183305.txt">Table of n, a(n) for n = 1..200</a> %F A183305 Empirical: a(n)=5*a(n-1)-6*a(n-2)+a(n-3)+a(n-4)-9*a(n-5)+4*a(n-6)+a(n-7)+28*a(n-8)-16*a(n-9)-3*a(n-10)+2*a(n-11)-6*a(n-12)+2*a(n-13)-a(n-14) for n>15 %e A183305 Some solutions with a(1,1)=0 for 4X4 %e A183305 ..0..1..0..1....0..1..1..0....0..0..1..0....0..1..0..0....0..1..0..1 %e A183305 ..1..0..1..0....1..0..0..1....1..1..0..1....1..0..1..1....0..1..1..0 %e A183305 ..0..1..1..0....0..0..1..0....0..1..1..0....0..0..1..0....1..0..1..1 %e A183305 ..0..1..0..1....1..1..0..1....1..0..0..1....1..1..0..1....0..1..0..0 %K A183305 nonn %O A183305 1,1 %A A183305 _R. H. Hardin_ Jan 03 2011