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 A210919 Number of n X n 0..3 symmetric matrices with every element equal to zero or one horizontal and vertical neighbor, and new values 0..3 introduced in lower triangle row major order 0
 1, 2, 50, 5036, 1650722, 1726180511, 5772723512117, 61704243727319597, 2108342605082097217766, 230275999931688657463304318, 80396959992514189225966415632361 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE Some solutions for n=4 ..0..1..0..1....0..1..2..0....0..1..2..0....0..1..1..3....0..1..0..3 ..1..2..0..2....1..0..2..1....1..0..3..0....1..2..0..3....1..2..0..2 ..0..0..3..0....2..2..1..0....2..3..2..3....1..0..3..2....0..0..3..0 ..1..2..0..3....0..1..0..1....0..0..3..2....3..3..2..1....3..2..0..3 CROSSREFS Sequence in context: A356611 A079198 A274485 * A210924 A355629 A203766 Adjacent sequences: A210916 A210917 A210918 * A210920 A210921 A210922 KEYWORD nonn AUTHOR R. H. Hardin Mar 29 2012 STATUS approved

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Last modified February 2 16:53 EST 2023. Contains 360023 sequences. (Running on oeis4.)