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A208858 Number of n X 2 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or left-upward diagonal neighbors. 1
2, 11, 127, 1691, 23047, 315203, 4313071, 59022155, 807696535, 11053048211, 151257183487, 2069902880411, 28325913895207, 387630456564323, 5304590398318351, 72591507756551915, 993389989178417335 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A208864.
LINKS
FORMULA
Empirical: a(n) = 17*a(n-1) - 48*a(n-2) + 36*a(n-3) for n>4.
Empirical g.f.: x*(2 - 23*x + 36*x^2 - 12*x^3) / ((1 - 2*x)*(1 - 15*x + 18*x^2)). - Colin Barker, Jul 07 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..0....0..0....0..1....0..0....0..0....0..0....0..0....0..1
..0..1....0..1....1..1....1..1....1..0....0..1....0..1....1..1....0..1....1..2
..0..2....1..0....0..2....2..0....0..1....0..1....1..2....0..0....1..0....3..3
..1..3....1..2....2..0....1..2....0..1....0..2....2..0....0..1....2..2....3..1
CROSSREFS
Cf. A208864.
Sequence in context: A112864 A077391 A104087 * A283537 A154596 A337458
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 02 2012
STATUS
approved

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Last modified June 25 15:24 EDT 2024. Contains 373705 sequences. (Running on oeis4.)