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A210176
Number of (n+1) X 2 0..3 arrays containing all values 0..3 with every 2 X 2 subblock having three or four distinct values, and new values 0..3 introduced in row major order.
1
1, 51, 744, 9042, 103752, 1165620, 12988416, 144259560, 1600182816, 17740623696, 196642606464, 2179465613472, 24155044021632, 267707038144320, 2966944305186816, 32881987112668800, 364423467992173056
OFFSET
1,2
COMMENTS
Column 1 of A210183.
LINKS
FORMULA
Empirical: a(n) = 14*a(n-1) - 26*a(n-2) - 68*a(n-3) - 24*a(n-4).
Empirical g.f.: x*(1 + x)*(1 + 36*x + 20*x^2) / ((1 - 4*x - 2*x^2)*(1 - 10*x - 12*x^2)). - Colin Barker, Jul 15 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..1....0..0....0..0....0..0....0..0....0..1....0..0....0..0
..1..2....1..2....2..3....1..2....1..2....1..2....1..2....2..0....1..2....1..2
..0..1....3..1....2..0....1..3....0..1....3..1....1..3....0..1....3..2....1..3
..1..2....2..1....1..1....0..3....1..2....1..2....3..2....3..0....0..1....2..1
..3..3....0..1....2..3....3..1....0..3....0..1....0..0....2..0....0..2....2..3
CROSSREFS
Cf. A210183.
Sequence in context: A160835 A231750 A232020 * A224474 A201140 A210079
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 18 2012
STATUS
approved