A256728 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum zero and no antidiagonal sum three.

384, 2304, 13056, 73984, 413440, 2310400, 12865280, 71639296, 398552832, 2217279744, 12332535552, 68593705216, 381495652096, 2121753477376, 11800309124864, 65628404490496, 364996358434560, 2029949420601600

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 56*a(n-3) + 64*a(n-4).

Empirical g.f.: 128*x*(3 - 3*x - 24*x^2 + 32*x^3) / ((1 - 7*x + 8*x^2)*(1 - 8*x^2)). - Colin Barker, Dec 20 2018

Example

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

Crossrefs

Column 1 of A256735.

Sequence in context: A134175 A233886 A256735 * A236029 A252904 A252899

Adjacent sequences: A256725 A256726 A256727 * A256729 A256730 A256731

Keyword

nonn

Author

R. H. Hardin, Apr 09 2015

Status

approved