A210910 - OEIS

A210910

Number of n X n 0..2 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

1, 3, 23, 401, 13984, 970083, 132838634, 35924634547, 19142194392682, 20077037322761989, 41429745313369193161, 168164789977096418548306

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A233218 A114601 A178315 * A280654 A118195 A055326

Adjacent sequences: A210907 A210908 A210909 * A210911 A210912 A210913

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

STATUS

approved