A252223 Number of (n+2) X (3+2) 0..2 arrays with every 3 X 3 subblock row and column sum 2 3 or 4 and every diagonal and antidiagonal sum not 2 3 or 4.

812, 3066, 9566, 24932, 73826, 231254, 718514, 2208224, 6786900, 20903022, 64397300, 198324482, 610719174, 1880738882, 5791972896, 17837010452, 54930710846, 169164213764, 520957422434, 1604338505654, 4940713885010

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - a(n-2) + 3*a(n-3) + 3*a(n-4) - a(n-5) - a(n-6) for n>8.

Empirical g.f.: 2*x*(406 + 315*x + 590*x^2 - 1568*x^3 - 1519*x^4 - 1188*x^5 - 519*x^6 + 147*x^7) / ((1 - x + 2*x^2 - x^3)*(1 - 2*x - 3*x^2 - x^3)). - Colin Barker, Dec 02 2018

Example

Some solutions for n=4:
..2..0..2..0..1....2..0..2..1..1....1..0..2..0..1....1..2..1..1..1
..0..2..0..2..0....0..2..0..2..0....1..2..0..2..1....1..0..2..0..1
..2..0..2..0..1....2..0..2..0..1....2..0..2..0..1....0..2..0..2..0
..0..2..0..2..1....0..2..0..2..1....0..2..0..2..0....1..0..2..0..2
..2..0..2..0..1....2..0..2..0..2....2..0..2..0..2....1..2..0..2..1
..1..2..0..1..1....1..2..0..1..1....1..1..1..2..1....2..0..2..1..1

Crossrefs

Column 3 of A252228.

Sequence in context: A183216 A093633 A045228 * A158667 A035854 A099116

Adjacent sequences: A252220 A252221 A252222 * A252224 A252225 A252226

Keyword

nonn

Author

R. H. Hardin, Dec 15 2014

Status

approved