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A201620 Number of nX3 0..3 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor 1
4, 56, 378, 3699, 31802, 256836, 1877283, 12466658, 75830797, 426330762, 2234037739, 10991599638, 51096736814, 225648517165, 951032245643, 3840801817887, 14914920467311, 55860582248737, 202312954584987 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A201625

LINKS

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

FORMULA

Empirical: a(n) is a polynomial of degree 63 for n>35

EXAMPLE

Some solutions for n=5

..0..0..1....0..0..2....0..0..1....0..1..1....0..0..0....0..2..3....0..0..1

..0..0..1....0..0..2....0..0..1....0..1..1....0..3..3....0..2..3....0..0..1

..0..1..3....1..1..2....0..1..1....3..1..2....1..0..0....1..1..0....2..2..2

..0..1..3....3..3..0....3..1..3....3..2..2....1..3..3....3..0..0....2..3..3

..0..2..2....3..3..0....3..3..3....3..3..2....2..2..2....3..1..1....3..3..3

CROSSREFS

Sequence in context: A201448 A195577 A255011 * A204108 A077122 A020540

Adjacent sequences:  A201617 A201618 A201619 * A201621 A201622 A201623

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 03 2011

STATUS

approved

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Last modified June 21 16:12 EDT 2018. Contains 305624 sequences. (Running on oeis4.)