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 A183577 #7 Jul 22 2025 09:06:11 %S A183577 2,14,78,407,2216,12024,65277,354615,1926386,10465655,56858572, %T A183577 308906899,1678265791,9117888439,49536803509,269129777690, %U A183577 1462162196206,7943819360442,43158185018445,234475238671702,1273886693818638 %N A183577 Half the number of nX2 0..3 arrays with each element equal to either the maximum or the minimum of its horizontal and vertical neighbors. %C A183577 Column 2 of A183584 %H A183577 R. H. Hardin, <a href="/A183577/b183577.txt">Table of n, a(n) for n = 1..200</a> %F A183577 Empirical: a(n)=7*a(n-1)-8*a(n-2)+4*a(n-3)-41*a(n-4)+20*a(n-5)-13*a(n-6)+130*a(n-7)+32*a(n-8)+94*a(n-9)-118*a(n-10)-88*a(n-11)-93*a(n-12)-a(n-13)+20*a(n-14) %e A183577 Some solutions with a(1,1)<=1 for 3X2 %e A183577 ..0..0....1..3....1..1....0..2....0..0....1..1....1..0....0..0....1..1....0..0 %e A183577 ..0..0....1..3....2..1....0..2....3..0....2..0....1..0....0..0....0..0....2..2 %e A183577 ..0..0....1..1....2..2....0..2....3..0....2..0....1..0....1..1....2..2....0..0 %K A183577 nonn %O A183577 1,1 %A A183577 _R. H. Hardin_ Jan 05 2011