A187993 Number of nondecreasing arrangements of n numbers x(i) in -(2n-2)..(2n-2) with the sum of sign(x(i))*x(i)^2 zero.

1, 3, 5, 34, 117, 862, 5443, 43750, 354103, 3099873, 27848450, 258912232, 2459308291, 23849609290, 235048481924, 2350490503424, 23798290970741, 243632773686215, 2518607289874541, 26265548152662462, 276073967613403738, 2922502585387560322, 31138106756017576520

Offset

1,2

Links

Max Alekseyev, Table of n, a(n) for n = 1..30

Example

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

Crossrefs

Diagonal of A188002.

Cf. A379451.

Sequence in context: A222484 A354849 A222630 * A221158 A068111 A162444

Adjacent sequences: A187990 A187991 A187992 * A187994 A187995 A187996

Keyword

nonn

Author

R. H. Hardin, Mar 18 2011

Extensions

a(14)-a(15) from R. J. Mathar, May 10 2023

Terms a(16) onward from Max Alekseyev, Nov 15 2025

Status

approved