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A207143 Number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor. 1
30, 48, 56, 95, 110, 187, 218, 371, 434, 740, 866, 1478, 1730, 2954, 3458, 5906, 6914, 11810, 13826, 23618, 27650, 47234, 55298, 94466, 110594, 188930, 221186, 377858, 442370, 755714, 884738, 1511426, 1769474, 3022850, 3538946, 6045698, 7077890 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A207149.
LINKS
FORMULA
Empirical: a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3) for n>9.
Empirical g.f.: x*(30 + 18*x - 52*x^2 + 3*x^3 - x^4 - x^5 + x^6 - x^7 + x^8) / ((1 - x)*(1 - 2*x^2)). - Colin Barker, Jun 19 2018
EXAMPLE
Some solutions for n=4:
..1..2..0....1..1..0....0..1..0....2..1..0....2..1..2....0..1..0....2..2..0
..2..0..2....2..0..1....1..0..1....1..0..1....1..2..1....2..0..1....2..0..2
..0..2..0....0..2..0....0..1..0....0..1..0....2..1..2....0..2..0....0..2..0
..1..0..2....1..0..2....1..0..1....1..0..1....1..2..1....1..0..2....2..0..2
..0..1..1....0..1..1....0..1..1....0..1..0....2..1..2....0..1..1....0..2..2
CROSSREFS
Cf. A207149.
Sequence in context: A075290 A281919 A004222 * A004223 A230558 A272949
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 15 2012
STATUS
approved

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Last modified July 22 05:57 EDT 2024. Contains 374481 sequences. (Running on oeis4.)