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A247720
Number of length n+3 0..2 arrays with no disjoint pairs in any consecutive four terms having the same sum
1
48, 90, 172, 334, 656, 1300, 2584, 5148, 10272, 20520, 41008, 81976, 163904, 327760, 655456, 1310832, 2621568, 5243040, 10485952, 20971744, 41943296, 83886400, 167772544, 335544768, 671089152, 1342177920, 2684355328, 5368710016
OFFSET
1,1
COMMENTS
Column 2 of A247726
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +2*a(n-4) -4*a(n-5).
Empirical G.f.: -2*x*(-24+3*x+4*x^2+5*x^3+54*x^4) / ( (2*x-1)*(2*x^4-1) ). - R. J. Mathar, Sep 23 2014
EXAMPLE
Some solutions for n=6
..1....2....2....2....2....2....1....0....2....2....1....0....1....0....1....2
..0....1....0....0....0....0....0....0....0....2....2....2....2....2....0....2
..0....0....1....2....2....0....0....2....1....2....0....2....0....2....2....1
..0....0....2....1....1....1....2....0....2....0....0....1....2....1....0....2
..1....0....0....0....2....0....1....1....0....2....1....2....2....2....0....2
..0....1....0....2....2....2....2....0....0....2....2....2....2....0....0....0
..0....2....0....0....2....2....0....2....1....1....0....0....1....0....1....1
..2....0....1....1....0....1....2....0....0....0....2....1....2....1....0....2
..1....2....0....0....1....2....2....0....0....2....2....2....2....2....2....0
CROSSREFS
Sequence in context: A260106 A260099 A224546 * A204647 A260980 A260070
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 23 2014
STATUS
approved