A229751 Number of defective 4-colorings of an n X 4 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..3 order.

3, 422, 2347, 6561, 15075, 32548, 69198, 147376, 315786, 680124, 1468934, 3174760, 6855906, 14780020, 31793694, 68231136, 146079674, 312025516, 665011638, 1414360024, 3002176530, 6360776292, 13453355726, 28408158544, 59894811114

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 33*a(n-2) + 63*a(n-3) - 66*a(n-4) + 36*a(n-5) - 8*a(n-6) for n>11.

Empirical g.f.: x*(3 + 395*x - 1352*x^2 - 825*x^3 + 7089*x^4 - 6731*x^5 + 132*x^6 + 863*x^7 - 58*x^8 - 60*x^9 + 8*x^10) / ((1 - x)^3*(1 - 2*x)^3). - Colin Barker, Sep 21 2018

Example

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

Crossrefs

Column 4 of A229755.

Sequence in context: A333134 A366355 A213001 * A172859 A087771 A332143

Adjacent sequences: A229748 A229749 A229750 * A229752 A229753 A229754

Keyword

nonn

Author

R. H. Hardin, Sep 28 2013

Status

approved