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A202981 Number of n X n 0..2 arrays with every nonzero element less than or equal to some NW, E or S neighbor 0
1, 9, 1233, 595202, 2075667829, 54374200726981, 9811910575029966643, 12034608427204532840940835, 102201977619119405092991507364893, 6015924965468985859548914234181730364514 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Diagonal of A202988

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

Some solutions for n=3

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

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

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

CROSSREFS

Sequence in context: A174253 A266602 A084149 * A276823 A020261 A266864

Adjacent sequences:  A202978 A202979 A202980 * A202982 A202983 A202984

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 26 2011

STATUS

approved

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Last modified December 4 04:22 EST 2020. Contains 338921 sequences. (Running on oeis4.)