A255075 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum one and no antidiagonal sum one.

208, 676, 2444, 8836, 31960, 115600, 418200, 1512900, 5473500, 19802500, 71645000, 259210000, 937825000, 3393062500, 12276187500, 44415562500, 160696875000, 581406250000, 2103546875000, 7610701562500, 27535773437500, 99625351562500

Offset

1,1

Links

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

Formula

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

Empirical g.f.: 4*x*(52 - 91*x - 234*x^2 + 454*x^3 - 130*x^4) / ((1 - 5*x + 5*x^2)*(1 - 5*x^2)). - Colin Barker, Dec 18 2018

Example

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

Crossrefs

Column 1 of A255082.

Sequence in context: A131686 A235273 A255082 * A304281 A234549 A234543

Adjacent sequences: A255072 A255073 A255074 * A255076 A255077 A255078

Keyword

nonn

Author

R. H. Hardin, Feb 14 2015

Status

approved