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A210815 Number of (n+1)X(n+1) 0..3 symmetric matrices containing all values 0..3 with every 2X2 subblock having one or two distinct values, and new values 0..3 introduced in lower triangle row major order 0
0, 1, 168, 22071, 4205467, 1371990855, 822477585796, 938225630752531, 2077579958754422544, 9041912808668087622556, 77978293195183315063183805, 1340161768266449394440151104678 (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=3

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

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

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

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

CROSSREFS

Sequence in context: A075920 A181202 A076006 * A282375 A289327 A130215

Adjacent sequences:  A210812 A210813 A210814 * A210816 A210817 A210818

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 27 2012

STATUS

approved

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Last modified October 26 14:28 EDT 2021. Contains 348267 sequences. (Running on oeis4.)