A224663 Number of n X n 0..6 matrices with each 2X2 subblock idempotent

7, 28, 162, 268, 596, 1118, 2166, 4038, 7488, 13686, 24818, 44640, 79796, 141848, 250966, 442168, 776152, 1357850, 2368298, 4119186

Offset

1,1

Comments

Column 6 of A224665

Links

Table of n, a(n) for n=1..20.

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
..1..1..2....1..1..6....1..1..4....0..0..0....0..1..0....1..1..0....1..0..3
..0..0..0....0..0..0....0..0..0....0..0..0....0..1..0....0..0..0....1..0..1
..2..1..1....3..1..1....6..1..1....4..1..1....0..1..0....0..0..1....2..0..1

Crossrefs

Sequence in context: A026664 A304520 A335759 * A378554 A203296 A355155

Adjacent sequences: A224660 A224661 A224662 * A224664 A224665 A224666

Keyword

nonn

Author

R. H. Hardin Apr 14 2013

Status

approved