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A210900 Number of n X n 0..2 symmetric matrices with every element equal to zero, one or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order 1
1, 5, 102, 6390, 1086041, 502575673, 633196217205, 2172041686544831, 20286478141700961127, 515885869356108286483984, 35719903989356689494965133243, 6734055759629373955660905711394302 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..13

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A231830 A260024 A123626 * A197799 A266903 A052138

Adjacent sequences:  A210897 A210898 A210899 * A210901 A210902 A210903

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

STATUS

approved

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Last modified January 28 20:53 EST 2022. Contains 350662 sequences. (Running on oeis4.)