A233083 Number of 2 X n 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 in row major order.

3, 14, 95, 662, 4631, 32414, 226895, 1588262, 11117831, 77824814, 544773695, 3813415862, 26693911031, 186857377214, 1308001640495, 9156011483462, 64092080384231, 448644562689614, 3140511938827295, 21983583571791062

Offset: 1

Author

R. H. Hardin, Dec 03 2013

Keywords

• nonn

Examples

			Some solutions for n=5:
..0..1..1..3..2....0..0..1..0..2....0..1..1..3..3....0..1..0..2..0
..1..3..2..2..3....2..0..1..0..0....1..1..3..3..3....0..1..0..0..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Row 2 of A233082.

Formula

Empirical: a(n) = 8*a(n-1) - 7*a(n-2) for n>3.

Conjectures from Colin Barker, Oct 07 2018: (Start)

G.f.: x*(3 - 10*x + 4*x^2) / ((1 - x)*(1 - 7*x)).

a(n) = (49 + 27*7^n) / 98 for n>1.

(End)