A229582 Number of defective 3-colorings of an n X 4 0..2 array connected horizontally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order.

6, 116, 1620, 19764, 224532, 2440692, 25745364, 265720500, 2697594516, 27033340788, 268094978388, 2636009007156, 25732468879380, 249667710249204, 2409688805255892, 23151313964420532, 221538858133842324

Offset

1,1

Links

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

Formula

Empirical: a(n) = 18*a(n-1) - 81*a(n-2) for n>3.

Conjectures from Colin Barker, Sep 19 2018: (Start)

G.f.: 2*x*(3 + 4*x + 9*x^2) / (1 - 9*x)^2.

a(n) = 4 * 9^(n - 2) * (16*n - 3) for n>1.

(End)

Example

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

Crossrefs

Column 4 of A229586.

Sequence in context: A278752 A003425 A052465 * A113015 A362765 A024275

Adjacent sequences: A229579 A229580 A229581 * A229583 A229584 A229585

Keyword

nonn

Author

R. H. Hardin, Sep 26 2013

Status

approved