A252527 Number of (n+2) X (3+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.

621, 341, 466, 610, 1114, 1748, 2332, 4244, 6760, 9112, 16552, 26576, 36016, 65360, 105376, 143200, 259744, 419648, 571072, 1035584, 1674880, 2280832, 4135552, 6692096, 9116416, 16528640, 26753536, 36451840, 66087424, 106984448, 145779712

Offset: 1

Author

R. H. Hardin, Dec 18 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 3 of A252532.

Formula

Empirical: a(n) = 6*a(n-3) - 8*a(n-6) for n>8.

Empirical g.f.: x*(621 + 341*x + 466*x^2 - 3116*x^3 - 932*x^4 - 1048*x^5 + 3640*x^6 + 288*x^7) / ((1 - 2*x^3)*(1 - 4*x^3)). - Colin Barker, Dec 04 2018