A252531 Number of (n+2) X (7+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 2 3 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 2 3 6 or 7.

1200, 1468, 2404, 3160, 11456, 19232, 25280, 91648, 153856, 202240, 733184, 1230848, 1617920, 5865472, 9846784, 12943360, 46923776, 78774272, 103546880, 375390208, 630194176, 828375040, 3003121664, 5041553408, 6627000320

Offset: 1

Author

R. H. Hardin, Dec 18 2014

Keywords

• nonn

Examples

			Some solutions for n=4:
..3..2..2..3..2..2..3..2..2....1..1..0..1..1..0..1..1..0
..3..1..3..3..1..3..3..1..3....0..1..1..0..1..1..0..1..1
..2..2..3..2..2..3..2..2..3....0..3..0..0..3..0..0..3..0
..3..2..2..3..2..2..3..2..2....1..1..0..1..1..0..1..1..0
..3..0..3..3..1..3..3..0..3....0..1..1..0..1..1..0..1..1
..2..2..3..2..2..3..2..2..3....3..3..0..0..2..0..0..2..0
		

Links

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

Crossrefs

Column 7 of A252532.

Formula

Empirical: a(n) = 8*a(n-3) for n>5.

Empirical g.f.: 4*x*(300 + 367*x + 601*x^2 - 1610*x^3 - 72*x^4) / ((1 - 2*x)*(1 + 2*x + 4*x^2)). - Colin Barker, Dec 04 2018