A224662 Number of n X n 0..5 matrices with each 2X2 subblock idempotent.

6, 24, 128, 222, 500, 956, 1876, 3538, 6622, 12200, 22274, 40302, 72418, 129332, 229780, 406378, 715800, 1256248, 2197512, 3832510, 6665570, 11563364, 20012598

Offset: 1

Author

R. H. Hardin Apr 14 2013

Keywords

• nonn

Comments

Column 5 of A224665

Examples

			Some solutions for n=3
..0..0..0....1..1..4....1..0..5....1..1..3....1..0..2....1..0..2....1..0..0
..0..0..0....0..0..0....1..0..1....0..0..0....1..0..1....1..0..1....1..0..1
..2..1..1....0..0..0....0..0..1....5..1..1....2..0..1....4..0..1....3..0..1
		

Formula

Empirical: a(n) = 6*a(n-1) -12*a(n-2) +5*a(n-3) +12*a(n-4) -12*a(n-5) -3*a(n-6) +6*a(n-7) -a(n-9) for n>10