A229573 Number of defective 4-colorings of an n X 3 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..3 order.

2, 26, 76, 171, 362, 757, 1584, 3323, 6982, 14673, 30812, 64615, 135282, 282749, 589960, 1228947, 2556062, 5308585, 11010228, 22806719, 47186122, 97517781, 201326816, 415236331, 855638262, 1761607937, 3623878924, 7449084183

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 12*a(n-3) - 4*a(n-4) for n>5.

Empirical g.f.: x*(2 + 14*x - 54*x^2 + 29*x^3 + 20*x^4) / ((1 - x)^2*(1 - 2*x)^2). - Colin Barker, Sep 19 2018

Example

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

Crossrefs

Column 3 of A229578.

Sequence in context: A247957 A152997 A345693 * A337396 A067204 A202077

Adjacent sequences: A229570 A229571 A229572 * A229574 A229575 A229576

Keyword

nonn

Author

R. H. Hardin, Sep 26 2013

Status

approved