A268013 Number of n X 1 0..2 arrays with every repeated value in every row and column greater than or equal to the previous repeated value.

3, 9, 27, 78, 222, 622, 1722, 4719, 12821, 34575, 92637, 246788, 654120, 1725900, 4535172, 11872941, 30977943, 80575109, 208983471, 540606474, 1395061474, 3591893274, 9228660318, 23664610747, 60570324105, 154763821419, 394795932561

Offset: 1

Author

R. H. Hardin, Jan 24 2016

Keywords

• nonn

Comments

Column 1 of A268019.

Examples

			Some solutions for n=8:
..1....2....2....1....2....1....0....0....2....1....2....0....2....2....2....2
..0....1....2....2....0....1....0....0....0....0....0....2....1....0....0....0
..2....1....2....0....0....2....1....1....2....1....2....0....2....2....0....2
..0....1....2....2....0....2....0....2....0....1....0....0....0....0....1....2
..0....0....0....2....2....1....0....2....2....2....2....1....0....1....0....0
..1....2....1....1....1....0....2....0....2....2....1....1....0....2....1....2
..1....1....2....2....2....2....2....2....0....0....0....2....0....2....2....2
..2....1....1....0....0....1....0....1....1....2....0....0....0....1....0....1
		

Links

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

Crossrefs

Cf. A268019.

Formula

Empirical: a(n) = 6*a(n-1) - 9*a(n-2) - 4*a(n-3) + 9*a(n-4) + 6*a(n-5) + a(n-6).

Empirical g.f.: x*(3 - 9*x + 9*x^3 + 6*x^4 + x^5) / (1 - 2*x - x^2)^3. - Colin Barker, Feb 26 2018