A224558 Number of (n+2) X 9 0..1 matrices with each 3 X 3 subblock idempotent.

669, 492, 620, 749, 988, 1298, 1668, 2201, 2961, 4001, 5477, 7609, 10670, 15089, 21515, 30870, 44505, 64420, 93537, 136129, 198469, 289752, 423446, 619292, 906226, 1326652, 1942715, 2845496, 4168480, 6107297, 8948658, 13112759, 19215426

Offset

1,1

Comments

Column 7 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*(669 - 2184*x + 2666*x^2 - 2124*x^3 + 1928*x^4 - 1299*x^5 + 332*x^6 + 5*x^7) / ((1 - x)^3*(1 - x - x^3)). - Colin Barker, Sep 01 2018

Example

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

Crossrefs

Cf. A224559.

Sequence in context: A092797 A105212 A067875 * A250670 A235101 A232388

Adjacent sequences: A224555 A224556 A224557 * A224559 A224560 A224561

Keyword

nonn

Author

R. H. Hardin, Apr 10 2013

Status

approved