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A206728
Number of n X 2 0..2 arrays avoiding the pattern z-1 z-1 z in any row, column or nw-to-se diagonal.
4
9, 81, 625, 4761, 36100, 273529, 2073600, 15721225, 119202724, 903844096, 6853356225, 51965305681, 394024865796, 2987677680100, 22653944467456, 171772609502025, 1302458795084836, 9875840600125696, 74883157850128384
OFFSET
1,1
COMMENTS
Column 2 of A206734.
LINKS
FORMULA
Empirical: a(n) = 9*a(n-1) -6*a(n-2) -43*a(n-3) +34*a(n-4) +162*a(n-5) -133*a(n-6) -13*a(n-7) +62*a(n-8) -14*a(n-9) -15*a(n-10) -6*a(n-11) +8*a(n-12) -a(n-13) -2*a(n-14) +a(n-15).
a(n) = A206727(n)^2. - Mark van Hoeij, May 14 2013
EXAMPLE
Some solutions for n=4:
..0..2....1..2....2..0....0..2....2..1....2..0....2..0....1..2....0..1....0..2
..0..1....2..0....1..2....1..1....2..1....0..2....1..2....2..2....2..1....0..2
..2..0....0..1....0..2....2..0....2..0....1..0....0..2....1..2....2..0....2..2
..1..0....1..2....1..0....0..1....1..2....1..2....2..0....2..2....0..0....0..2
CROSSREFS
Sequence in context: A213297 A272243 A272242 * A206857 A073531 A206694
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 11 2012
STATUS
approved