

A229572


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


1



1, 6, 26, 80, 216, 544, 1312, 3072, 7040, 15872, 35328, 77824, 169984, 368640, 794624, 1703936, 3637248, 7733248, 16384000, 34603008, 72876032, 153092096, 320864256, 671088640, 1400897536, 2919235584, 6073352192, 12616466432, 26172456960
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OFFSET

1,2


LINKS

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


FORMULA

Empirical: a(n) = 4*a(n1)  4*a(n2) for n>3.
Conjectures from Colin Barker, Sep 19 2018: (Start)
G.f.: x*(1 + 2*x + 6*x^2) / (1  2*x)^2.
a(n) = 2^(n2) * (7*n8) for n>1.
(End)


EXAMPLE

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


CROSSREFS

Column 2 of A229578.
Sequence in context: A255870 A286188 A094162 * A316160 A224035 A172207
Adjacent sequences: A229569 A229570 A229571 * A229573 A229574 A229575


KEYWORD

nonn


AUTHOR

R. H. Hardin, Sep 26 2013


STATUS

approved



