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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. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A305664 A152517 A213001 * A172859 A087771 A277234

Adjacent sequences:  A229748 A229749 A229750 * A229752 A229753 A229754

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 28 2013

STATUS

approved

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Last modified November 13 23:48 EST 2019. Contains 329106 sequences. (Running on oeis4.)