

A229473


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


1



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

1,2


LINKS

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


FORMULA

Empirical: a(n) = 8*a(n1)  16*a(n2) 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*n5) * (10*n9) 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: A180286 A054613 A270239 * A141834 A344065 A180355
Adjacent sequences: A229470 A229471 A229472 * A229474 A229475 A229476


KEYWORD

nonn


AUTHOR

R. H. Hardin, Sep 24 2013


STATUS

approved



