A232923 - OEIS

%I #8 Oct 06 2018 06:15:13

%S 81,162,1122,5808,33702,186720,1054446,5907444,33206862,186398988,

%T 1046931522,5878727460,33013750890,185390166264,1041086668026,

%U 5846332684128,32830815650766,184365298149288,1035325615443174

%N Number of 4 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, diagonally or antidiagonally.

%H R. H. Hardin, <a href="/A232923/b232923.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) + 16*a(n-2) - 3*a(n-3) - 25*a(n-4) + 2*a(n-5) + 4*a(n-6) for n>7.

%F Empirical g.f.: 3*x*(27 - 27*x - 220*x^2 + 31*x^3 + 279*x^4 - 20*x^5 - 40*x^6) / (1 - 3*x - 16*x^2 + 3*x^3 + 25*x^4 - 2*x^5 - 4*x^6). - _Colin Barker_, Oct 06 2018

%e Some solutions for n=5:

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

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

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

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

%Y Row 4 of A232920.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 02 2013