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A213692 Half the number of (n+1)X(n+1) symmetric 0..3 arrays with no 2X2 subblock summing to 6 0
28, 1320, 208072, 109820000, 193946752094, 1146407046198040, 22678299640600736258, 1501445596428593204920908, 332684482425964910985336666019, 246706401290583205383638262307956104 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A213697

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

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

CROSSREFS

Sequence in context: A061321 A281328 A091993 * A118705 A249348 A013926

Adjacent sequences:  A213689 A213690 A213691 * A213693 A213694 A213695

KEYWORD

nonn

AUTHOR

R. H. Hardin Jun 18 2012

STATUS

approved

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Last modified August 8 11:31 EDT 2020. Contains 336298 sequences. (Running on oeis4.)