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 A211082 1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, one or three horizontal and vertical neighbors 0
 1, 9, 297, 31671, 11073510, 12788362323, 48662429782212, 610280363553528555, 25226141633402684949288, 3436779288522895580112954426, 1543230902313982340399083345635951 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE Some solutions for n=4 ..1..0..0..1....2..0..0..0....1..2..3..3....1..3..3..2....0..2..2..3 ..0..1..2..2....0..1..0..1....2..3..2..0....3..2..1..0....2..1..0..1 ..0..2..0..3....0..0..1..0....3..2..3..2....3..1..0..3....2..0..3..1 ..1..2..3..1....0..1..0..1....3..0..2..0....2..0..3..2....3..1..1..2 CROSSREFS Sequence in context: A012838 A216966 A211077 * A061685 A183549 A104775 Adjacent sequences:  A211079 A211080 A211081 * A211083 A211084 A211085 KEYWORD nonn AUTHOR R. H. Hardin Mar 31 2012 STATUS approved

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Last modified August 17 08:02 EDT 2022. Contains 356184 sequences. (Running on oeis4.)