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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A247726

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

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

Adjacent sequences:  A247717 A247718 A247719 * A247721 A247722 A247723

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 23 2014

STATUS

approved

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Last modified October 28 06:41 EDT 2021. Contains 348316 sequences. (Running on oeis4.)