A199894 Number of -4..4 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative

1, 9, 37, 209, 1043, 5725, 30199, 164993, 890299, 4877477, 26632013, 146499083, 805700567, 4449304857, 24590147861, 136249639279, 755738351775, 4199211521573, 23357174342185, 130088542750275, 725223072283995

Offset

1,2

Comments

Column 4 of A199898

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Example

Some solutions for n=6
.-2....1....0...-2....3....3....1....3...-2....0....3...-1....1....2....4....1
..3....0....4....0....0...-3...-1....0....2...-2....0....0...-1...-3...-2...-1
..0....0...-4....0...-2....0....1...-4...-1....0....0...-1....4....3....1....4
..1...-4....3....0....1...-3...-2....2....0....2....0....2...-2....0...-2....0
.-2....0...-3...-2...-2....3....2...-4....1....0....1...-4....2....2....2...-4
..0....3....0....4....0....0...-1....3....0....0...-4....4...-4...-4...-3....0

Crossrefs

Sequence in context: A201441 A183327 A364700 * A232258 A370244 A370269

Adjacent sequences: A199891 A199892 A199893 * A199895 A199896 A199897

Keyword

nonn

Author

R. H. Hardin Nov 11 2011

Status

approved