A233157 Number of 4 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally or antidiagonally.

81, 384, 2592, 17496, 121176, 842616, 5871528, 40931568, 285366888, 1989557640, 13871104848, 96708780360, 674249796360, 4700843090928, 32774093555112, 228499694410248, 1593090904911120, 11106967289377032, 77437340197187976

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 15*a(n-2) + 6*a(n-3) for n>7.

Empirical g.f.: 3*x*(27 - 115*x + 117*x^2 - 186*x^3 + 96*x^4 - 360*x^5 + 216*x^6) / (1 - 9*x + 15*x^2 - 6*x^3). - Colin Barker, Oct 09 2018

Example

Some solutions for n=5:
..0..1..0..0..0....1..2..2..1..2....0..0..1..2..1....2..1..0..0..1
..0..0..0..0..0....2..1..2..2..2....1..2..1..0..1....0..0..1..2..1
..1..0..0..0..0....2..2..2..2..1....1..0..1..2..2....0..0..1..2..1
..0..1..0..0..1....2..1..2..2..2....1..2..1..2..2....1..0..1..0..1

Crossrefs

Row 4 of A233155.

Sequence in context: A205737 A236035 A236028 * A237108 A237101 A236618

Adjacent sequences: A233154 A233155 A233156 * A233158 A233159 A233160

Keyword

nonn

Author

R. H. Hardin, Dec 05 2013

Status

approved