A224605 Number of (n+2) X 9 0..2 matrices with each 3 X 3 subblock idempotent.

1694, 1221, 1455, 1657, 2091, 2656, 3308, 4272, 5672, 7588, 10325, 14312, 20058, 28377, 40512, 58215, 84052, 121832, 177116, 258031, 376513, 550059, 804293, 1176775, 1722562, 2522335, 3694335, 5411860, 7928889, 11617642, 17023637

Offset

1,1

Comments

Column 7 of A224606.

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*(1694 - 5555*x + 6735*x^2 - 5307*x^3 + 4864*x^4 - 3239*x^5 + 796*x^6 + 5*x^7) / ((1 - x)^3*(1 - x - x^3)). - Colin Barker, Sep 02 2018

Example

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

Crossrefs

Cf. A224606.

Sequence in context: A126720 A366644 A325884 * A252570 A235182 A237170

Adjacent sequences: A224602 A224603 A224604 * A224606 A224607 A224608

Keyword

nonn

Author

R. H. Hardin, Apr 11 2013

Status

approved