A204625 Number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock having unequal diagonal elements or unequal antidiagonal elements, and new values 0..2 introduced in row major order.

768, 43734, 2490558, 141832254, 8077061502, 459972403614, 26194503047262, 1491724252385406, 84950695233299262, 4837771196037723486, 275501337345598245918, 15689246928705157494846, 893471050128160321852158

Offset: 1

Author

R. H. Hardin, Jan 17 2012

Keywords

• nonn

Comments

Column 3 of A204630.

Examples

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

Links

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

Crossrefs

Cf. A204630.

Formula

Empirical: a(n) = 60*a(n-1) - 175*a(n-2) + 68*a(n-3).

Empirical g.f.: 6*x*(128 - 391*x + 153*x^2) / (1 - 60*x + 175*x^2 - 68*x^3). - Colin Barker, Jun 07 2018