A208559 Number of 7 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 0 1 1 vertically.

20, 400, 1260, 11020, 52000, 351140, 1913940, 11836400, 67894220, 407225740, 2378376000, 14112662980, 82952260180, 490344818000, 2888730695340, 17052623706380, 100542287612000, 593228737061860, 3498693917381460

Offset: 1

Author

R. H. Hardin, Feb 28 2012

Keywords

• nonn

Comments

Row 7 of A208555.

Examples

			Some solutions for n=4:
..0..1..0..0....0..1..1..1....0..1..0..1....0..1..0..1....1..1..0..1
..1..1..0..1....1..0..1..0....0..1..0..0....0..1..1..0....1..0..1..1
..0..1..0..0....0..1..1..1....0..1..0..0....0..1..0..0....1..1..0..0
..0..1..0..0....1..0..1..0....0..1..0..0....0..1..1..0....1..0..1..1
..0..1..0..0....0..1..1..1....0..1..0..0....0..1..0..0....0..1..0..0
..0..1..0..0....1..0..1..0....0..1..0..0....0..1..1..0....1..0..1..1
..0..1..0..0....0..1..0..0....0..1..0..0....0..1..0..0....0..1..0..0
		

Links

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

Crossrefs

Cf. A208555.

Formula

Empirical: a(n) = a(n-1) + 31*a(n-2) + 12*a(n-3) - 144*a(n-4).

Empirical g.f.: 20*x*(1 + 19*x + 12*x^2 - 144*x^3) / (1 - x - 31*x^2 - 12*x^3 + 144*x^4). - Colin Barker, Jul 05 2018