A255220 Number of (n+2)X(n+2) 0..1 arrays with no 3x3 subblock diagonal sum 0 and no antidiagonal sum 0 and no row sum 2 and no column sum 2

23, 28, 46, 70, 106, 160, 238, 352, 520, 766, 1126, 1654, 2428, 3562, 5224, 7660, 11230, 16462, 24130, 35368, 51838, 75976, 111352, 163198, 239182, 350542, 513748, 752938, 1103488, 1617244

Offset

1,1

Comments

Diagonal of A255228

Links

Table of n, a(n) for n=1..30.

Formula

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

Empirical g.f. 23*x -2*x^2*(-14+5*x-3*x^2+8*x^3) / (x-1) / (x^3+x-1) . - R. J. Mathar, Nov 09 2018

Empirical: a(n) = -8 +6*(3*A000930(n) + A000930(n-1) +2*A000930(n-2)) for n>1. - R. J. Mathar, Nov 09 2018

Example

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

Crossrefs

Cf. A255228

Sequence in context: A219259 A116224 A127495 * A060703 A061753 A166063

Adjacent sequences: A255217 A255218 A255219 * A255221 A255222 A255223

Keyword

nonn

Author

R. H. Hardin, Feb 17 2015

Status

approved