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A211093 1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors 0
1, 10, 247, 15457, 2424088, 951410443, 932290081063, 2278103185689373, 13868101018687422769, 210186367992374120026696 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A034222 A197437 A268545 * A108792 A265854 A128013

Adjacent sequences:  A211090 A211091 A211092 * A211094 A211095 A211096

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved

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Last modified October 27 19:59 EDT 2020. Contains 338036 sequences. (Running on oeis4.)