A187996 Number of nondecreasing arrangements of n numbers x(i) in -(n+1)..(n+1) with the sum of sign(x(i))*x(i)^2 zero.

1, 4, 5, 25, 64, 286, 1055, 5191, 24135, 122238, 626982, 3324754, 17890884, 98093994, 544680909, 3062711643, 17400096265, 99802843644, 577238731571, 3364142278629, 19740895907880, 116567717909224, 692260264168512, 4132754144726272, 24791787193993220

Offset

1,2

Links

Table of n, a(n) for n=1..25.

Example

Some solutions for n=4
.-4...-2...-5...-5...-1...-2...-3...-4...-3...-4...-2...-5...-2...-3...-3...-4
.-4...-2...-3...-1...-1...-1...-1...-3....1...-1....0....0...-2....0...-3....0
..4....2....3....1....1....1....1....0....2....1....0....3...-1....0....3....0
..4....2....5....5....1....2....3....5....2....4....2....4....3....3....3....4

Crossrefs

Column 3 of A188002.

Sequence in context: A333321 A047168 A220538 * A394408 A144053 A084465

Adjacent sequences: A187993 A187994 A187995 * A187997 A187998 A187999

Keyword

nonn

Author

R. H. Hardin, Mar 18 2011

Extensions

Terms from a(18) on from R. J. Mathar, May 10 2023

Status

approved