A224600 Number of (n+2)X4 0..2 matrices with each 3X3 subblock idempotent

178, 272, 371, 449, 630, 894, 1221, 1707, 2440, 3476, 4979, 7189, 10414, 15114, 22001, 32083, 46840, 68452, 100119, 146509, 214482, 314086, 460049, 673947, 987416, 1446808, 2120063, 3106745, 4552782, 6672030, 9777921, 14329803, 21000892

Offset

1,1

Comments

Column 2 of A224606

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -2*a(n-2) -a(n-3) +a(n-4) -a(n-5) +2*a(n-6) -a(n-7) for n>9.

Empirical g.f.: 178*x + 272*x^2 -x^3*(-371 +664*x -25*x^2 -273*x^3 +123*x^4 -384*x^5 +268*x^6) / ( (1+x)*(x^3+x-1)*(x-1)^3 ). - R. J. Mathar, Aug 22 2016

Example

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

Crossrefs

Sequence in context: A046436 A114081 A217037 * A279093 A297400 A297600

Adjacent sequences: A224597 A224598 A224599 * A224601 A224602 A224603

Keyword

nonn

Author

R. H. Hardin Apr 11 2013

Status

approved