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A188247 Number of arrangements of n+2 nonzero numbers x(i) in -7..7 with the sum of x(i)*x(i+1) equal to zero 0
196, 532, 10564, 75080, 1142180, 11953848, 168083116, 2026547348, 27843005992, 355600251460, 4851985495460, 63719148177636, 867980001700376, 11577646834184824, 157763834094118596 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A188249

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

Some solutions for n=4

.-3...-1...-3....2....4...-6....5....3...-4....2...-1....4...-6...-6....3...-6

.-7...-7...-1...-1...-1...-1...-1....6...-5...-5....1....3...-6....3...-1...-4

..1....2...-6...-2....2...-6....1...-1....3....6...-2...-6....3....2...-2....3

..4....6...-2....3....5....1....4...-6...-3....2....2...-5...-6....6....4...-2

.-2....5....3....3....2....2...-2....2....2....7....7....3...-7....1....3...-6

..5...-7...-5...-1...-7...-4...-5...-3....5....2...-1...-3....6...-6...-1....3

CROSSREFS

Sequence in context: A119667 A023108 A092231 * A211851 A089493 A088753

Adjacent sequences:  A188244 A188245 A188246 * A188248 A188249 A188250

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 25 2011

STATUS

approved

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Last modified August 16 00:08 EDT 2022. Contains 356150 sequences. (Running on oeis4.)