

A238518


Number of (n+1) X (1+1) 0..3 arrays with no element equal to all horizontal neighbors or equal to all vertical neighbors.


1



84, 588, 7056, 74676, 812028, 8777664, 95006100, 1028017452, 11124397872, 120377861940, 1302620868444, 14095781346528, 152531780288916, 1650560738719116, 17860873095687888, 193274188450247604
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OFFSET

1,1


LINKS

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


FORMULA

Empirical: a(n) = 9*a(n1) + 21*a(n2)  14*a(n3).
Empirical g.f.: 84*x*(1  2*x) / (1  9*x  21*x^2 + 14*x^3).  Colin Barker, Oct 24 2018


EXAMPLE

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


CROSSREFS

Column 1 of A238523.
Sequence in context: A008429 A175813 A238523 * A264654 A230907 A220016
Adjacent sequences: A238515 A238516 A238517 * A238519 A238520 A238521


KEYWORD

nonn


AUTHOR

R. H. Hardin, Feb 28 2014


STATUS

approved



