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 A210929 Number of n X n 0..3 symmetric matrices with every element equal to zero or two horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order 0
 1, 3, 42, 2316, 320744, 106842320, 85415568160, 163885278844480, 754594332585922688, 8337847863812427968768, 221082535444417970063262208 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..11. EXAMPLE Some solutions for n=4 ..0..0..1..3....0..1..0..1....0..1..0..2....0..1..2..3....0..1..3..0 ..0..0..2..1....1..2..3..2....1..0..2..3....1..0..3..2....1..2..0..2 ..1..2..0..2....0..3..0..0....0..2..0..2....2..3..2..3....3..0..2..1 ..3..1..2..1....1..2..0..0....2..3..2..3....3..2..3..0....0..2..1..3 CROSSREFS Sequence in context: A333323 A331705 A156108 * A083402 A145984 A213956 Adjacent sequences: A210926 A210927 A210928 * A210930 A210931 A210932 KEYWORD nonn AUTHOR R. H. Hardin Mar 29 2012 STATUS approved

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Last modified October 2 09:54 EDT 2023. Contains 365833 sequences. (Running on oeis4.)