A199903 Number of -2..2 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2)

1, 4, 12, 24, 82, 232, 654, 2044, 6096, 18564, 57500, 177032, 550098, 1715956, 5359158, 16799508, 52760640, 165976252, 523094304, 1650781728, 5216112586, 16501009804, 52252555938, 165618780196, 525388548976, 1667965025692

Offset

1,2

Comments

Column 2 of A199909

Links

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

Example

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

Crossrefs

Sequence in context: A282512 A025543 A064354 * A218034 A377211 A140813

Adjacent sequences: A199900 A199901 A199902 * A199904 A199905 A199906

Keyword

nonn

Author

R. H. Hardin Nov 11 2011

Status

approved