A247528 Number of length n+3 0..3 arrays with some disjoint pairs in every consecutive four terms having the same sum.

88, 136, 220, 364, 604, 1018, 1732, 2956, 5050, 8638, 14794, 25348, 43438, 74446, 127606, 218740, 374968, 642784, 1101898, 1888954, 3238192, 5551168, 9516268, 16313584, 27966124, 47941900, 82186078, 140890372, 241526284, 414044950

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) - a(n-3) + a(n-4) - a(n-5) - a(n-6) + a(n-7).

Empirical g.f.: 2*x*(44 - 20*x - 26*x^2 + 6*x^3 - 38*x^4 - 9*x^5 + 32*x^6) / ((1 - x)*(1 - x - x^2 - x^4 + x^6)). - Colin Barker, Nov 07 2018

Example

Some solutions for n=6:
..2....0....2....0....0....2....3....3....2....2....0....1....3....3....0....2
..3....1....0....1....1....3....2....2....1....1....1....1....0....3....1....1
..1....3....1....1....3....1....2....1....2....1....0....0....0....2....1....0
..0....2....3....2....2....2....1....2....3....2....1....2....3....2....2....3
..2....2....2....2....0....0....1....1....2....2....2....1....3....1....0....2
..1....1....0....1....1....1....2....2....1....1....1....3....0....3....1....1
..1....1....1....3....1....1....0....1....2....3....2....0....0....2....1....2
..0....0....1....0....0....2....1....0....3....0....1....2....3....2....2....3
..2....2....2....2....0....2....3....1....2....2....2....1....3....3....0....0

Crossrefs

Column 3 of A247533.

Sequence in context: A225136 A039445 A300144 * A346774 A249555 A226587

Adjacent sequences: A247525 A247526 A247527 * A247529 A247530 A247531

Keyword

nonn

Author

R. H. Hardin, Sep 18 2014

Status

approved