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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
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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 26 2014
STATUS
approved