A255221 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 and no antidiagonal sum 0 and no row sum 2 and no column sum 2.

23, 22, 31, 43, 61, 88, 127, 184, 268, 391, 571, 835, 1222, 1789, 2620, 3838, 5623, 8239, 12073, 17692, 25927, 37996, 55684, 81607, 119599, 175279, 256882, 376477, 551752, 808630, 1185103, 1736851, 2545477, 3730576, 5467423, 8012896, 11743468

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(23 - 24*x + 10*x^2 - 20*x^3 + 7*x^4) / ((1 - x)*(1 - x - x^3)). - Colin Barker, Dec 19 2018

Example

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

Crossrefs

Column 1 of A255228.

Sequence in context: A004464 A255228 A374669 * A072135 A204633 A010862

Adjacent sequences: A255218 A255219 A255220 * A255222 A255223 A255224

Keyword

nonn

Author

R. H. Hardin, Feb 17 2015

Status

approved