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A209101
Number of 2 X n 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.
1
2, 11, 76, 520, 3552, 24256, 165632, 1131008, 7723008, 52736000, 360103936, 2458943488, 16790716416, 114654183424, 782907736064, 5346028421120, 36504965480448, 249271496474624, 1702132247953408, 11622886011830272
OFFSET
1,1
COMMENTS
Row 2 of A209100.
LINKS
FORMULA
Empirical: a(n) = 8*a(n-1) - 8*a(n-2) for n>3.
Empirical g.f.: x*(2 - 5*x + 4*x^2) / (1 - 8*x + 8*x^2). - Colin Barker, Jul 08 2018
EXAMPLE
Some solutions for n=4:
..0..0..1..2....0..0..1..1....0..0..0..1....0..0..1..1....0..0..0..0
..1..2..0..0....2..0..0..1....2..1..0..2....1..0..2..0....1..1..2..0
CROSSREFS
Cf. A209100.
Sequence in context: A055085 A354298 A350580 * A118802 A365146 A350680
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 05 2012
STATUS
approved