A278183 - OEIS

%I #8 Feb 08 2019 12:30:03

%S 0,3,28,200,1532,11794,90538,695252,5339294,41003018,314882364,

%T 2418138526,18570087298,142608927356,1095164819630,8410314860218,

%U 64586987065356,495995568270926,3808996439085090,29251176423848812

%N Number of n X 2 0..3 arrays with every element plus 1 mod 4 equal to some element 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="/A278183/b278183.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 8*a(n-1) - 4*a(n-2) + 15*a(n-3) - 26*a(n-4) + 14*a(n-5) - 16*a(n-6).

%F Empirical g.f.: x^2*(3 + 4*x - 12*x^2 - x^3 - 4*x^4) / (1 - 8*x + 4*x^2 - 15*x^3 + 26*x^4 - 14*x^5 + 16*x^6). - _Colin Barker_, Feb 08 2019

%e Some solutions for n=4:

%e ..0..1. .0..2. .0..2. .0..1. .0..3. .0..1. .0..3. .0..1. .0..1. .0..3

%e ..3..2. .1..3. .1..3. .3..2. .1..2. .0..2. .1..3. .0..2. .1..2. .1..0

%e ..2..1. .2..0. .1..0. .3..1. .1..0. .3..3. .2..0. .1..3. .0..3. .2..0

%e ..1..1. .3..2. .2..3. .0..3. .3..3. .2..1. .1..0. .3..0. .1..2. .3..1

%Y Column 2 of A278188.

%K nonn

%O 1,2

%A _R. H. Hardin_, Nov 14 2016