A250413 Number of length n+1 0..2 arrays with the sum of the minimum of each adjacent pair multiplied by some arrangement of +-1 equal to zero.

5, 17, 38, 125, 335, 1061, 3069, 9495, 28221, 86149, 258252, 782393, 2350442, 7090347, 21303611, 64109181, 192553620, 578665211, 1737374865, 5217197093, 15659477401, 47004010481, 141055441813, 423295193635, 1270118805510

Offset: 1

Author

R. H. Hardin, Nov 22 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 2 of A250419.

Formula

Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 40*a(n-3) + 59*a(n-4) + 68*a(n-5) - 146*a(n-6) - 14*a(n-7) + 91*a(n-8) - 8*a(n-9) - 12*a(n-10).

Empirical g.f.: x*(5 - 13*x - 49*x^2 + 148*x^3 + 84*x^4 - 397*x^5 + 40*x^6 + 257*x^7 - 36*x^8 - 36*x^9) / ((1 - x)*(1 - 2*x)*(1 + 2*x)*(1 - 3*x)*(1 - 2*x - x^2 + x^3)*(1 - 3*x^2 - x^3)). - Colin Barker, Nov 14 2018