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

1,1

Comments

Column 1 of A268019.

Links

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

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

Example

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

Crossrefs

Cf. A268019.

Sequence in context: A152169 A370142 A241574 * A269613 A006810 A090401

Adjacent sequences: A268010 A268011 A268012 * A268014 A268015 A268016

Keyword

nonn

Author

R. H. Hardin, Jan 24 2016

Status

approved