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A188115 Number of strictly increasing arrangements of n nonzero numbers in -n..n with sum zero 1
0, 2, 2, 8, 16, 52, 152, 484, 1536, 5064, 16946, 57528, 197616, 686588, 2407538, 8510428, 30300268, 108575996, 391301260, 1417520988, 5159160792, 18857230104, 69193592020, 254802169904, 941383915572, 3488574124056, 12964318919492 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A188122

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..31

EXAMPLE

Some solutions for n=6

.-5...-5...-6...-6...-5...-6...-6...-6...-6...-5...-6...-4...-6...-6...-5...-6

.-4...-4...-4...-5...-4...-5...-5...-3...-4...-3...-5...-3...-4...-2...-4...-4

.-1...-1...-2...-1...-2...-4...-3...-2...-1...-1...-1...-1...-2...-1...-2...-1

..1....1....2....3....2....4....3....2....2....2....2....1....3....1....1....2

..4....3....4....4....4....5....5....3....3....3....4....2....4....2....4....4

..5....6....6....5....5....6....6....6....6....4....6....5....5....6....6....5

CROSSREFS

Sequence in context: A220589 A109190 A016120 * A085542 A239682 A009725

Adjacent sequences:  A188112 A188113 A188114 * A188116 A188117 A188118

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 21 2011

STATUS

approved

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Last modified February 22 18:16 EST 2018. Contains 299469 sequences. (Running on oeis4.)