A266423 Number of n X 3 binary arrays with rows and columns lexicographically nondecreasing and column sums nondecreasing.

4, 14, 39, 96, 212, 433, 826, 1493, 2575, 4270, 6841, 10639, 16114, 23845, 34555, 49147, 68725, 94637, 128501, 172257, 228199, 299035, 387927, 498560, 635189, 802719, 1006760, 1253717, 1550855, 1906400, 2329613, 2830904, 3421916, 4115651

Offset: 1

Author

R. H. Hardin, Dec 29 2015

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 3 of A266428.

Formula

Empirical: a(n) = 5*a(n-1) - 8*a(n-2) + a(n-3) + 9*a(n-4) - 6*a(n-5) - 6*a(n-7) + 9*a(n-8) + a(n-9) - 8*a(n-10) + 5*a(n-11) - a(n-12).

Empirical g.f.: x*(4 - 6*x + x^2 + 9*x^3 - 6*x^4 - 6*x^6 + 9*x^7 + x^8 - 8*x^9 + 5*x^10 - x^11) / ((1 - x)^8*(1 + x)^2*(1 + x + x^2)). - Colin Barker, Jan 09 2019