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A207066
Number of n X 6 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 1 vertically.
1
21, 441, 2499, 8799, 23856, 54684, 111426, 208026, 362943, 599907, 948717, 1446081, 2136498, 3073182, 4319028, 5947620, 8044281, 10707165, 14048391, 18195219, 23291268, 29497776, 36994902, 45983070, 56684355, 69343911, 84231441
OFFSET
1,1
COMMENTS
Column 6 of A207068.
LINKS
FORMULA
Empirical: a(n) = (7/120)*n^6 + (147/40)*n^5 + (49/3)*n^4 + (91/8)*n^3 - (707/120)*n^2 - (91/20)*n.
Conjectures from Colin Barker, Jun 18 2018: (Start)
G.f.: 21*x*(1 + 14*x - 7*x^2 - 8*x^3 + 2*x^4) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)
EXAMPLE
Some solutions for n=4:
..0..0..0..0..0..0....0..1..1..1..0..0....1..0..1..1..1..0....1..1..1..1..1..0
..1..0..1..1..1..0....1..0..1..1..1..0....0..1..1..1..1..0....0..0..0..0..0..0
..0..0..0..0..0..0....1..0..0..0..0..0....0..1..1..1..0..0....0..0..0..0..0..0
..0..0..0..0..0..0....1..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..0
CROSSREFS
Cf. A207068.
Sequence in context: A207517 A207246 A208167 * A207121 A207440 A188691
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 14 2012
STATUS
approved