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

1,1

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) - 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

Example

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

Crossrefs

Column 2 of A250419.

Sequence in context: A212968 A127744 A122734 * A163686 A147165 A147257

Adjacent sequences: A250410 A250411 A250412 * A250414 A250415 A250416

Keyword

nonn

Author

R. H. Hardin, Nov 22 2014

Status

approved