A229535 Number of defective 3-colorings of a 2 X n 0..2 array connected horizontally, diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order.

0, 4, 8, 36, 112, 368, 1152, 3568, 10880, 32832, 98176, 291392, 859392, 2520832, 7359488, 21397248, 61984768, 178979840, 515303424, 1479746560, 4239208448, 12118487040, 34574761984, 98466394112, 279960846336, 794771341312

Offset

1,2

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 8*a(n-3) - 4*a(n-4).

Empirical g.f.: 4*x^2*(1 - x)^2 / (1 - 2*x - 2*x^2)^2. - Colin Barker, Sep 18 2018

Example

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

Crossrefs

Row 2 of A229534.

Sequence in context: A149112 A221842 A100214 * A309618 A047710 A335991

Adjacent sequences: A229532 A229533 A229534 * A229536 A229537 A229538

Keyword

nonn

Author

R. H. Hardin, Sep 25 2013

Status

approved