A229474 Number of defective 4-colorings of an n X 3 0..3 array connected horizontally, antidiagonally and vertically with exactly one mistake, and colors introduced in row-major 0..3 order.

2, 42, 420, 3328, 23964, 163528, 1077588, 6927888, 43728652, 272112472, 1674170052, 10205294240, 61731029116, 370982129640, 2217078993972, 13186003918640, 78093132909036, 460783597042808, 2709856102785444

Offset

1,1

Links

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

Formula

Empirical: a(n) = 14*a(n-1) - 65*a(n-2) + 112*a(n-3) - 64*a(n-4) for n>5.

Empirical g.f.: 2*x*(1 + 7*x - 19*x^2 - 23*x^3 + 48*x^4) / (1 - 7*x + 8*x^2)^2. - Colin Barker, Sep 18 2018

Example

Some solutions for n=4:
..0..0..1....0..1..0....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2
..2..3..0....2..3..2....3..3..0....3..0..3....3..0..3....3..2..0....2..0..1
..0..2..1....0..1..3....0..2..1....1..3..0....3..1..2....0..3..2....3..2..0
..1..3..2....2..0..3....1..0..2....0..1..3....2..3..0....1..0..3....3..1..2

Crossrefs

Column 3 of A229479.

Sequence in context: A202865 A360786 A070808 * A157056 A180425 A140170

Adjacent sequences: A229471 A229472 A229473 * A229475 A229476 A229477

Keyword

nonn

Author

R. H. Hardin, Sep 24 2013

Status

approved