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A184489
Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock sum greater than 4.
1
31, 165, 792, 3971, 19593, 97312, 482071, 2390621, 11850280, 58751643, 291260673, 1443961520, 7158542031, 35489140405, 175940409400, 872240066291, 4324205636281, 21437626315584, 106278895767879, 526886873434445
OFFSET
1,1
COMMENTS
Column 1 of A184497.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + 11*a(n-2) - 4*a(n-3) - 12*a(n-4).
Empirical g.f.: x*(31 + 72*x - 44*x^2 - 96*x^3) / ((1 + 2*x)*(1 - 5*x - x^2 + 6*x^3)). - Colin Barker, Apr 12 2018
EXAMPLE
Some solutions for 3 X 2:
..2..0....1..2....2..1....2..1....2..1....1..0....2..2....1..2....1..2....2..2
..2..1....1..1....2..2....2..2....1..1....2..2....2..2....2..2....2..2....1..2
..2..1....2..1....0..2....1..0....1..2....2..1....1..0....1..2....2..0....2..2
CROSSREFS
Cf. A184497.
Sequence in context: A142306 A296114 A184497 * A140540 A183877 A107953
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 15 2011
STATUS
approved