A278274 - OEIS

%I #8 Feb 09 2019 08:49:27

%S 0,2,5,16,49,153,476,1483,4619,14388,44817,139601,434844,1354499,

%T 4219139,13142228,40936825,127514425,397195644,1237227707,3853849915,

%U 12004386164,37392552993,116474345313,362806816604,1130109689139,3520187193395

%N Number of n X 2 0..1 arrays with every element both equal and not equal to some elements at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero.

%H R. H. Hardin, <a href="/A278274/b278274.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) + a(n-2) - 2*a(n-3) for n>4.

%F Empirical g.f.: x^2*(1 - x)*(2 + x) / (1 - 3*x - x^2 + 2*x^3). - _Colin Barker_, Feb 09 2019

%e Some solutions for n=4:

%e ..0..0. .0..1. .0..1. .0..1. .0..1. .0..0. .0..1. .0..0. .0..0. .0..0

%e ..1..1. .0..1. .0..1. .0..1. .0..1. .1..1. .0..1. .1..1. .1..1. .1..1

%e ..0..0. .0..1. .0..0. .1..0. .0..1. .1..0. .0..1. .1..0. .1..1. .0..1

%e ..1..1. .1..1. .1..1. .1..1. .0..1. .1..0. .0..0. .0..0. .0..0. .0..1

%Y Column 2 of A278280.

%K nonn

%O 1,2

%A _R. H. Hardin_, Nov 16 2016