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 A210924 Number of n X n 0..3 symmetric matrices with every element equal to zero, one or three horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order. 0
 1, 2, 50, 5280, 1845589, 2131393730, 8110404963737, 101713393925588269, 4204356938900447492681, 572796548087149263352167089, 257205150385663723399847224344969 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE Some solutions for n=4 ..0..1..0..1....0..1..0..1....0..1..2..3....0..1..2..1....0..1..3..0 ..1..2..3..1....1..2..3..3....1..0..1..0....1..0..1..3....1..2..0..3 ..0..3..1..0....0..3..1..2....2..1..0..1....2..1..0..2....3..0..1..3 ..1..1..0..1....1..3..2..3....3..0..1..2....1..3..2..1....0..3..3..0 CROSSREFS Sequence in context: A079198 A274485 A210919 * A355629 A203766 A197487 Adjacent sequences: A210921 A210922 A210923 * A210925 A210926 A210927 KEYWORD nonn AUTHOR R. H. Hardin, Mar 29 2012 STATUS approved

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Last modified March 22 06:36 EDT 2023. Contains 361413 sequences. (Running on oeis4.)