A204146 Number of (n+2) X 3 0..2 arrays with every 3 X 3 subblock having equal diagonal elements or equal antidiagonal elements, and new values 0..2 introduced in row major order.

689, 3902, 22262, 127022, 724154, 4128422, 23538722, 134209022, 765199994, 4362829142, 24874945682, 141826072622, 808630145834, 4610454909062, 26286795128642, 149875795721822, 854526159123674, 4872133976736182

Offset

1,1

Comments

Column 1 of A204153.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) -5*a(n-2) +20*a(n-3) -4*a(n-4) -16*a(n-5).

Empirical g.f.: x*(689 - 232*x + 2295*x^2 - 820*x^3 - 1952*x^4) / ((1 - x)*(1 + 4*x^2)*(1 - 5*x - 4*x^2)). - Colin Barker, Jun 06 2018

Example

Some solutions for n=4:
..0..0..0....0..1..1....0..1..0....0..0..0....0..0..1....0..0..1....0..1..0
..1..0..1....2..0..2....0..0..1....1..0..1....0..1..0....2..0..1....1..0..0
..1..1..0....1..2..0....2..0..0....1..1..0....1..0..2....1..1..0....2..1..0
..0..0..1....0..0..2....2..2..0....2..0..1....1..1..0....1..0..2....0..2..1
..0..1..1....0..0..2....1..2..2....0..2..0....2..0..1....0..1..0....2..0..2
..1..2..2....2..1..0....0..1..2....2..2..2....0..2..0....2..2..1....1..2..0

Crossrefs

Cf. A204153.

Sequence in context: A025355 A025347 A204153 * A259512 A078877 A204145

Adjacent sequences: A204143 A204144 A204145 * A204147 A204148 A204149

Keyword

nonn

Author

R. H. Hardin, Jan 11 2012

Status

approved