A188116 Number of strictly increasing arrangements of n nonzero numbers in -(n+1)..(n+1) with sum zero

0, 3, 4, 16, 42, 137, 426, 1398, 4622, 15594, 53252, 184060, 642392, 2261829, 8024726, 28664946, 103015222, 372234190, 1351655526, 4930080182, 18055480464, 66371559466, 244817099870, 905883648170, 3361795172242, 12509691344838

Offset

1,2

Comments

Column 3 of A188122

Links

R. H. Hardin, Table of n, a(n) for n = 1..30

Example

Some solutions for n=6
.-4...-5...-7...-7...-7...-5...-7...-7...-7...-7...-6...-7...-5...-5...-7...-6
.-3...-3...-6...-5...-5...-4...-3...-4...-6...-4...-5...-6...-3...-2...-6...-4
.-2...-2...-1...-2....1...-3....1...-2....1...-2...-4...-2...-2...-1...-1...-2
..2...-1....3....2....2....3....2....3....3....2....2....3...-1....1....2....1
..3....5....5....5....4....4....3....4....4....4....6....5....4....3....5....5
..4....6....6....7....5....5....4....6....5....7....7....7....7....4....7....6

Crossrefs

Equals A188114(n+2)

Sequence in context: A329541 A154736 A188114 * A300316 A375471 A329546

Adjacent sequences: A188113 A188114 A188115 * A188117 A188118 A188119

Keyword

nonn

Author

R. H. Hardin Mar 21 2011

Status

approved