A266542 Number of n X 3 binary arrays with rows and columns lexicographically nondecreasing and row and column sums nonincreasing.

2, 3, 5, 6, 8, 11, 13, 16, 20, 23, 27, 32, 36, 41, 47, 52, 58, 65, 71, 78, 86, 93, 101, 110, 118, 127, 137, 146, 156, 167, 177, 188, 200, 211, 223, 236, 248, 261, 275, 288, 302, 317, 331, 346, 362, 377, 393, 410, 426, 443, 461, 478, 496, 515, 533, 552, 572, 591, 611, 632

Offset: 1

Author

R. H. Hardin, Dec 31 2015

Keywords

• nonn

Examples

			Some solutions for n=6:
..0..1..1....0..1..1....0..0..1....0..1..1....0..1..1....0..1..1....0..0..1
..0..1..1....1..0..1....0..1..0....1..0..0....0..1..1....0..1..1....0..0..1
..1..0..1....1..1..0....0..1..0....1..0..0....0..1..1....1..0..0....0..1..0
..1..0..1....1..1..0....1..0..0....1..0..0....1..0..0....1..0..0....0..1..0
..1..1..0....1..1..0....1..0..0....1..0..0....1..0..0....1..0..0....1..0..0
..1..1..0....1..1..0....1..0..0....1..0..0....1..0..0....1..0..0....1..0..0
		

Links

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

Crossrefs

Column 3 of A266547.

Formula

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

Empirical g.f.: x*(2 - x + x^2 - 3*x^3 + 2*x^4) / ((1 - x)^3*(1 + x + x^2)). - Colin Barker, Jan 10 2019