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A192640 Number of n X n symmetric 0..3 arrays with each element equal to at least one horizontal or vertical neighbor and any new values 0..3 introduced in lower triangular row major order 0
0, 1, 5, 137, 15055, 5986313, 7174532375, 25969938730579, 281423389721323932, 9146849687492666154781, 891167854920321677292610251 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

Some solutions for 6X6 containing a 3

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

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

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

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

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

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

CROSSREFS

Sequence in context: A012215 A012142 A012207 * A192641 A192642 A192643

Adjacent sequences:  A192637 A192638 A192639 * A192641 A192642 A192643

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 06 2011

STATUS

approved

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Last modified January 26 09:45 EST 2022. Contains 350598 sequences. (Running on oeis4.)