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A211094 1/4 the number of n X n 0..3 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors 0
0, 1, 13, 679, 87781, 35830153, 43041488701, 155818927585201, 1688540173184520937, 54881098051544185333873, 5347007129460018897210926833 (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 n=4

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

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

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

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

CROSSREFS

Sequence in context: A157027 A042307 A012746 * A290166 A113093 A195576

Adjacent sequences:  A211091 A211092 A211093 * A211095 A211096 A211097

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved

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Last modified October 24 18:26 EDT 2020. Contains 338009 sequences. (Running on oeis4.)