A229473 Number of defective 4-colorings of an n X 2 0..3 array connected horizontally, antidiagonally and vertically with exactly one mistake, and colors introduced in row-major 0..3 order.

1, 6, 42, 248, 1312, 6528, 31232, 145408, 663552, 2981888, 13238272, 58195968, 253755392, 1098907648, 4731174912, 20266876928, 86436216832, 367219703808, 1554778161152, 6562710028288, 27625229647872, 115998476730368

Offset

1,2

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) for n>4.

Conjectures from Colin Barker, Sep 17 2018: (Start)

G.f.: x*(1 - 2*x + 10*x^2 + 8*x^3) / (1 - 4*x)^2.

a(n) = 2^(2*n-5) * (10*n-9) for n>2.

(End)

Example

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

Crossrefs

Column 2 of A229479.

Sequence in context: A375259 A054613 A270239 * A141834 A344065 A180355

Adjacent sequences: A229470 A229471 A229472 * A229474 A229475 A229476

Keyword

nonn

Author

R. H. Hardin, Sep 24 2013

Status

approved