A255020 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 or 1 and no antidiagonal sum 0 or 1 and no row sum 0 or 1 and no column sum 0 or 1.

26, 54, 117, 269, 601, 1306, 2853, 6308, 13940, 30665, 67427, 148503, 327196, 720513, 1586270, 3492908, 7692097, 16938749, 37298997, 82133026, 180861833, 398268024, 877002280, 1931193369, 4252574871, 9364367191, 20620752180, 45407795437

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(26 + 28*x + 63*x^2 + 74*x^3 + 66*x^4 + 34*x^5 + 4*x^6) / (1 - x - 3*x^3 - 4*x^4 - 4*x^5 - 2*x^6). - Colin Barker, Dec 18 2018

Example

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

Crossrefs

Column 1 of A255027.

Sequence in context: A042350 A255027 A132767 * A184839 A038848 A245004

Adjacent sequences: A255017 A255018 A255019 * A255021 A255022 A255023

Keyword

nonn

Author

R. H. Hardin, Feb 13 2015

Status

approved