A184556 Number of (n+1) X 2 0..2 arrays with no 2 X 2 subblock summing to less than 4.

50, 336, 2167, 14180, 92429, 603249, 3935721, 25680486, 167558680, 1093290051, 7133495992, 46544663377, 303694712145, 1981548052649, 12929209539882, 84360538526896, 550435849841567, 3591485193655532, 23433731463177813

Offset: 1

Author

R. H. Hardin, Jan 17 2011

Keywords

• nonn

Comments

Column 1 of A184564.

Examples

			Some solutions for 3 X 2:
..2..1....1..2....0..0....1..2....0..2....1..0....2..0....2..0....2..0....2..2
..2..1....2..0....2..2....1..1....2..1....2..2....1..1....1..2....1..2....2..1
..1..0....2..0....0..0....2..2....0..2....0..2....2..1....0..1....2..2....1..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A184564.

Formula

Empirical: a(n) = 6*a(n-1) + 7*a(n-2) - 23*a(n-3) - 4*a(n-4) + 12*a(n-5).

Empirical g.f.: x*(50 + 36*x - 199*x^2 - 24*x^3 + 108*x^4) / ((1 + 2*x)*(1 - 8*x + 9*x^2 + 5*x^3 - 6*x^4)). - Colin Barker, Feb 27 2018