A187979 Number of nondecreasing arrangements of n numbers x(i) in -(2n-2)..(2n-2) with the sum of sign(x(i))*2^|x(i)| zero.

0, 2, 7, 30, 144, 597, 2742, 12148, 54696

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Example

All solutions for n=3
.-1...-3...-4...-3...-1...-2...-2
.-1....2....3...-3....0....1...-2
..2....2....3....4....0....1....3

Crossrefs

Diagonal of A187988.

Sequence in context: A006013 A358965 A368933 * A358964 A366055 A368932

Adjacent sequences: A187976 A187977 A187978 * A187980 A187981 A187982

Keyword

nonn,more

Author

R. H. Hardin, Mar 18 2011

Status

approved