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 A210904 Number of n X n 0..2 symmetric matrices with every element equal to zero, one, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order 1
 1, 5, 108, 7722, 1640736, 1033777404, 1931855614272, 10707730229352132, 176032647122454516348, 8583448868806218541129800, 1241375815868250678950006865216, 532497522393110319522129344363284548 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..16 EXAMPLE Some solutions for n=4 ..0..1..2..0....0..0..0..1....0..1..1..0....0..1..1..0....0..1..1..2 ..1..0..1..0....0..1..2..0....1..0..1..0....1..1..0..2....1..2..1..0 ..2..1..2..2....0..2..1..0....1..1..2..1....1..0..0..1....1..1..1..0 ..0..0..2..2....1..0..0..2....0..0..1..0....0..2..1..1....2..0..0..2 CROSSREFS Sequence in context: A204110 A113056 A220549 * A048564 A139971 A305095 Adjacent sequences:  A210901 A210902 A210903 * A210905 A210906 A210907 KEYWORD nonn AUTHOR R. H. Hardin Mar 29 2012 STATUS approved

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Last modified August 17 22:32 EDT 2018. Contains 313817 sequences. (Running on oeis4.)