A224725 Number of (n+3) X 8 0..2 matrices with each 4 X 4 subblock idempotent.

4257, 3123, 3775, 4209, 4498, 5727, 7575, 9778, 12188, 15746, 21068, 28510, 38276, 51515, 69988, 95816, 131320, 179974, 247009, 339781, 467963, 644706, 888388, 1224747, 1689190, 2330279, 3214950, 4435881, 6121153, 8447413, 11658240

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..159

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) - 2*a(n-3) + 4*a(n-4) - 3*a(n-5) + 2*a(n-7) - a(n-8) for n>10.

Empirical g.f.: x*(4257 - 9648*x + 2920*x^2 + 7644*x^3 - 11361*x^4 + 8480*x^5 + 2077*x^6 - 6522*x^7 + 2104*x^8 + 47*x^9) / ((1 - x)^3*(1 + x)*(1 - x - x^4)). - Colin Barker, Sep 04 2018

Example

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

Crossrefs

Column 5 of A224728.

Sequence in context: A237805 A031985 A138399 * A252030 A371569 A023346

Adjacent sequences: A224722 A224723 A224724 * A224726 A224727 A224728

Keyword

nonn

Author

R. H. Hardin, Apr 16 2013

Status

approved