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A211049 1/3 the number of n X n 0..2 symmetric matrices with every element equal to zero, one or three horizontal and vertical neighbors 0
1, 4, 48, 1232, 69944, 8897744, 2543744944, 1632807480048, 2350761948259496, 7595900369159613200, 55087633557679363709984, 896577592582670794898595216 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
EXAMPLE
Some solutions for n=4
..2..0..1..2....2..0..0..2....1..0..2..2....2..1..0..2....0..2..1..0
..0..1..2..1....0..1..2..2....0..2..0..1....1..0..2..0....2..1..0..1
..1..2..0..1....0..2..1..2....2..0..1..2....0..2..1..2....1..0..2..1
..2..1..1..2....2..2..2..0....2..1..2..0....2..0..2..1....0..1..1..0
CROSSREFS
Sequence in context: A024255 A211045 A296838 * A321076 A166231 A191952
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 30 2012
STATUS
approved

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Last modified June 13 17:32 EDT 2024. Contains 373391 sequences. (Running on oeis4.)