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A211052 1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors 1
0, 1, 9, 239, 14669, 2313041, 915560157, 915512113455, 2309733753013069, 14705975948890342013, 236286306641789616616527, 9580759647090339471565196845, 980341335177418943590433413869387 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
EXAMPLE
Some solutions for n=4
..0..0..1..0....1..1..2..2....1..1..0..0....2..2..0..2....0..0..1..1
..0..1..1..0....1..1..2..1....1..1..1..1....2..2..0..2....0..0..2..2
..1..1..1..1....2..2..1..1....0..1..1..0....0..0..2..2....1..2..2..2
..0..0..1..1....2..1..1..1....0..1..0..0....2..2..2..2....1..2..2..2
CROSSREFS
Sequence in context: A157569 A279492 A297747 * A085799 A278858 A274789
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 30 2012
STATUS
approved

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Last modified May 25 12:29 EDT 2024. Contains 372788 sequences. (Running on oeis4.)