A223970 Number of n X 3 0..2 arrays with rows and antidiagonals unimodal.

22, 484, 9515, 186004, 3628696, 70779056, 1380511272, 26926081924, 525177301935, 10243271456697, 199788923564609, 3896764235253108, 76004070829222317, 1482414237420454682, 28913608801546792225, 563942758255071088641

Offset: 1

Author

R. H. Hardin, Mar 30 2013

Keywords

• nonn

Comments

Column 3 of A223975.

Examples

			Some solutions for n=3:
..1..1..1....2..1..1....0..1..1....1..2..1....0..0..1....2..0..0....1..1..1
..2..2..1....2..1..0....2..1..1....1..2..2....1..2..2....1..1..1....1..2..2
..2..2..0....1..0..0....0..1..2....1..1..0....0..2..2....2..1..0....1..2..2
		

Links

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

Crossrefs

Cf. A223975.

Formula

Empirical: a(n) = 22*a(n-1) - 43*a(n-2) - 125*a(n-3) + 283*a(n-4) - 70*a(n-5) - 111*a(n-6) + 45*a(n-7).

Empirical g.f.: x*(22 - 187*x^2 + 236*x^3 + 27*x^4 - 141*x^5 + 45*x^6) / ((1 - x)*(1 - 3*x)*(1 - 18*x - 32*x^2 + 51*x^3 + 17*x^4 - 15*x^5)). - Colin Barker, Aug 25 2018