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A207689 Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 1 1 1 vertically. 1
9, 81, 100, 256, 576, 1156, 2500, 5476, 11664, 24964, 53824, 115600, 248004, 532900, 1144900, 2458624, 5280804, 11343424, 24364096, 52330756, 112402404, 241429444, 518563984, 1113823876, 2392383744, 5138595856, 11037183364, 23706760900 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 4 of A207693.
LINKS
FORMULA
Empirical: a(n) = a(n-1) + a(n-2) + 3*a(n-3) + a(n-4) - a(n-5) - a(n-6) for n>8.
Empirical g.f.: x*(9 + 72*x + 10*x^2 + 48*x^3 - 32*x^4 - 48*x^5 - 10*x^6 + 17*x^7) / ((1 + x^2 - x^3)*(1 - x - 2*x^2 - x^3)). - Colin Barker, Jun 25 2018
EXAMPLE
Some solutions for n=4:
..1..0..0..1....1..1..1..1....1..1..1..0....1..1..0..1....0..0..1..1
..1..1..1..1....0..0..1..1....1..0..0..1....0..0..1..1....1..1..1..0
..0..1..1..0....1..1..0..0....0..1..1..0....1..1..0..0....1..1..0..1
..1..0..0..1....1..0..0..1....0..1..1..1....0..1..1..0....0..0..1..1
CROSSREFS
Cf. A207693.
Sequence in context: A037414 A161147 A209220 * A209225 A208502 A175370
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 19 2012
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)