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

1,1

Comments

Column 5 of A224665

Links

Table of n, a(n) for n=1..23.

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

Example

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

Crossrefs

Sequence in context: A357194 A188232 A274072 * A200160 A219622 A052170

Adjacent sequences: A224659 A224660 A224661 * A224663 A224664 A224665

Keyword

nonn

Author

R. H. Hardin Apr 14 2013

Status

approved