A230185 Number of 2 X n 0..2 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value 2-x(i,j).

0, 9, 27, 159, 825, 4395, 23307, 123729, 656715, 3485775, 18502017, 98206299, 521266155, 2766812505, 14685878427, 77950719519, 413752211145, 2196142553835, 11656837079787, 61872964697889, 328413594039435, 1743176349744015

Offset: 1

Author

R. H. Hardin, Oct 11 2013

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 2 of A230184.

Formula

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

Empirical g.f.: 3*x^2*(3 - 3*x - 4*x^2 - 3*x^3 + 3*x^4) / ((1 - x)*(1 + x)*(1 - 4*x - 6*x^2 - 5*x^3)). - Colin Barker, Sep 21 2018