A187995 Number of nondecreasing arrangements of n numbers x(i) in -n..n with the sum of sign(x(i))*x(i)^2 zero.

1, 3, 4, 17, 45, 176, 644, 2983, 13675, 67487, 340192, 1775300, 9438436, 51112686, 281006680, 1565898705, 8826775421, 50268025897, 288898607594, 1674035743383, 9772219545537, 57429659103938, 339574982244340, 2019144043582652, 12067931396139136

Offset

1,2

Links

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

Example

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

Crossrefs

Column 2 of A188002.

Sequence in context: A096876 A257330 A115388 * A296277 A303480 A254200

Adjacent sequences: A187992 A187993 A187994 * A187996 A187997 A187998

Keyword

nonn

Author

R. H. Hardin, Mar 18 2011

Extensions

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

Status

approved