A232923 Number of 4 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, diagonally or antidiagonally.

81, 162, 1122, 5808, 33702, 186720, 1054446, 5907444, 33206862, 186398988, 1046931522, 5878727460, 33013750890, 185390166264, 1041086668026, 5846332684128, 32830815650766, 184365298149288, 1035325615443174

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 16*a(n-2) - 3*a(n-3) - 25*a(n-4) + 2*a(n-5) + 4*a(n-6) for n>7.

Empirical g.f.: 3*x*(27 - 27*x - 220*x^2 + 31*x^3 + 279*x^4 - 20*x^5 - 40*x^6) / (1 - 3*x - 16*x^2 + 3*x^3 + 25*x^4 - 2*x^5 - 4*x^6). - Colin Barker, Oct 06 2018

Example

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

Crossrefs

Row 4 of A232920.

Sequence in context: A031494 A043324 A267696 * A250655 A184003 A183995

Adjacent sequences: A232920 A232921 A232922 * A232924 A232925 A232926

Keyword

nonn

Author

R. H. Hardin, Dec 02 2013

Status

approved