A229504 Number of defective 3-colorings of an n X 2 0..2 array connected diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order.

0, 6, 48, 288, 1536, 7680, 36864, 172032, 786432, 3538944, 15728640, 69206016, 301989888, 1308622848, 5637144576, 24159191040, 103079215104, 438086664192, 1855425871872, 7834020347904, 32985348833280, 138538465099776

Offset

1,2

Comments

Column 2 of A229510.

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -16*a(n-2).

a(n) = 3/2*(n-1)*4^(n-1) for n = 1..210. - Jérôme Germoni, Sep 18 2015

Empirical g.f.: 6*x^2 / (1 - 4*x)^2. - Colin Barker, Jun 16 2017

Example

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

Crossrefs

Sequence in context: A293967 A246587 A340309 * A100740 A043020 A073994

Adjacent sequences: A229501 A229502 A229503 * A229505 A229506 A229507

Keyword

nonn

Author

R. H. Hardin, Sep 25 2013

Status

approved