A250640 Number of length n+1 0..2 arrays with the sum of the maximum of each adjacent pair multiplied by some arrangement of +-1 equal to zero.

1, 17, 23, 125, 280, 1061, 2870, 9495, 27507, 86149, 255704, 782393, 2341381, 7090347, 21271463, 64109181, 192439733, 578665211, 1736971814, 5217197093, 15658051930, 47004010481, 141050402559, 423295193635, 1270100996174

Offset

1,2

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 42*a(n-3) + 71*a(n-4) + 56*a(n-5) - 192*a(n-6) + 80*a(n-7) + 77*a(n-8) - 64*a(n-9) + 12*a(n-10).

Empirical g.f.: x*(1 + 11*x - 76*x^2 + 80*x^3 + 242*x^4 - 541*x^5 + 201*x^6 + 239*x^7 - 192*x^8 + 36*x^9) / ((1 - x)*(1 - 2*x)*(1 + 2*x)*(1 - 3*x)*(1 - 3*x^2 + x^3)*(1 - 2*x - x^2 + x^3)). - Colin Barker, Nov 15 2018

Example

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

Crossrefs

Column 2 of A250646.

Sequence in context: A100473 A060252 A127924 * A344636 A108260 A062628

Adjacent sequences: A250637 A250638 A250639 * A250641 A250642 A250643

Keyword

nonn

Author

R. H. Hardin, Nov 26 2014

Status

approved