A224555 Number of (n+2) X 6 0..1 matrices with each 3 X 3 subblock idempotent.

172, 174, 230, 286, 395, 551, 749, 1041, 1473, 2086, 2973, 4273, 6166, 8925, 12962, 18869, 27511, 40165, 58700, 85850, 125626, 183908, 269310, 394457, 577854, 846620, 1240499, 1817740, 2663711, 3903524, 5720540, 8383488, 12286209, 18005905

Offset

1,1

Comments

Column 4 of A224559.

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 5*a(n-3) - 4*a(n-4) + 3*a(n-5) - a(n-6) for n>8.

Empirical g.f.: x*(172 - 514*x + 566*x^2 - 450*x^3 + 449*x^4 - 283*x^5 + 55*x^6 + 4*x^7) / ((1 - x)^3*(1 - x - x^3)). - Colin Barker, Aug 31 2018

Example

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

Crossrefs

Cf. A224559.

Sequence in context: A252132 A252131 A223823 * A146339 A067356 A230371

Adjacent sequences: A224552 A224553 A224554 * A224556 A224557 A224558

Keyword

nonn

Author

R. H. Hardin, Apr 10 2013

Status

approved