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A210907 Number of n X n 0..2 symmetric matrices with every element equal to one or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order 0
0, 1, 2, 51, 1726, 153098, 28152650, 11567939904, 10468180657260, 20883980738963652, 92033224229940826385, 894504588855167462245204 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A106042 A222850 A089304 * A099368 A132492 A030264

Adjacent sequences:  A210904 A210905 A210906 * A210908 A210909 A210910

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

STATUS

approved

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Last modified June 27 13:59 EDT 2022. Contains 354896 sequences. (Running on oeis4.)