A199524 Number of -2..2 arrays x(0..n-1) of n elements with zero sum and no two consecutive zero elements

1, 4, 18, 72, 320, 1414, 6346, 28766, 131246, 602390, 2777638, 12857572, 59712940, 278096674, 1298309782, 6074112952, 28470828008, 133671581490, 628526085270, 2959291856816, 13950087683416, 65832860408434, 310987879638926

Offset

1,2

Comments

Column 2 of A199530

Links

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

Example

Some solutions for n=5
.-1....2....0...-1...-1....1...-2....2....1....1....0....0...-2....0...-1...-1
..0....1...-2....2....2....1....2...-2....0....2...-1....1....1....1....0...-2
.-2...-2....1....2....2....1...-2....2....1...-1...-1....1....2...-2....2....0
..1...-1....0...-2...-1...-2....2....0...-2....0....0...-1....1....2....1....2
..2....0....1...-1...-2...-1....0...-2....0...-2....2...-1...-2...-1...-2....1

Crossrefs

Sequence in context: A307566 A117615 A267450 * A083693 A123476 A343580

Adjacent sequences: A199521 A199522 A199523 * A199525 A199526 A199527

Keyword

nonn

Author

R. H. Hardin Nov 07 2011

Status

approved