A187994 - OEIS

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A187994

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

1, 2, 3, 12, 25, 106, 376, 1670, 7315, 35808, 176971, 910940, 4782220, 25663080, 139884020, 773939566, 4334475055, 24546800088, 140363450663, 809676156506, 4707204024505, 27561115755712, 162415358799242, 962751492786378, 5737779091829582

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OFFSET

1,2

COMMENTS

Column 1 of A188002

LINKS

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

EXAMPLE

All solutions for n=3

.-1...-2....0

..0....0....0

..1....2....0

CROSSREFS

Sequence in context: A148068 A148069 A148070 * A016021 A173669 A136703

Adjacent sequences: A187991 A187992 A187993 * A187995 A187996 A187997

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 18 2011

EXTENSIONS

Terms from a(19) on by R. J. Mathar, May 10 2023

STATUS

approved