A217639 Number of nX2 arrays of the minimum value of corresponding elements and their horizontal, vertical or antidiagonal neighbors in a random 0..2 nX2 array

3, 9, 27, 91, 293, 959, 3121, 10171, 33141, 107985, 351855, 1146471, 3735623, 12172023, 39660897, 129229689, 421077529, 1372024391, 4470556607, 14566706329, 47463649813, 154653907527, 503918919165, 1641951898617, 5350079020329

Offset

1,1

Comments

Column 2 of A217645

Links

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

Formula

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

Empirical: G.f.: x*(3+3*x+x^3-3*x^4+x^5) / ( 1-2*x-3*x^2-3*x^3-2*x^4+x^6 ). - R. J. Mathar, Jul 10 2015

Example

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

Crossrefs

Sequence in context: A148924 A113994 A302860 * A328080 A148925 A148926

Adjacent sequences: A217636 A217637 A217638 * A217640 A217641 A217642

Keyword

nonn

Author

R. H. Hardin Oct 09 2012

Status

approved