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A207863 Number of n X n nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal or vertical neighbor (colorings ignoring permutations of colors) 0
1, 4, 2052, 455546040, 103204230192540988 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Diagonal of A207868

LINKS

Table of n, a(n) for n=1..5.

EXAMPLE

Some solutions for n=5

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

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

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

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

..0..1..0..1..0....1..0..1..4..0....0..1..0..1..0....0..1..0..1..0

CROSSREFS

Sequence in context: A198716 A004815 A198907 * A220941 A012869 A172941

Adjacent sequences:  A207860 A207861 A207862 * A207864 A207865 A207866

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 21 2012

STATUS

approved

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Last modified July 21 02:02 EDT 2019. Contains 325189 sequences. (Running on oeis4.)