A218516 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..3 n X 2 array.

4, 36, 236, 1528, 9858, 63592, 410218, 2646208, 17069998, 110114102, 710317326, 4582071648, 29557748082, 190669317026, 1229957991200, 7934137929012, 51181052626992, 330155610028966, 2129747655406998, 13738446168804038

Offset: 1

Author

R. H. Hardin, Oct 31 2012

Keywords

• nonn

Comments

Column 2 of A218522.

Examples

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

Links

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

Crossrefs

Cf. A218522.

Formula

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

Empirical g.f.: 2*x*(2 + 6*x + 4*x^2 + 2*x^3 - x^4) / (1 - 6*x - 3*x^2 + 4*x^4 - x^5). - Colin Barker, Jul 24 2018