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A225988
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Number of pairs of orthogonal (-1,2) vectors of length 3*n.
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1
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9, 390, 20160, 1106424, 62606544, 3611217792, 211096262400, 12461757863808, 741242882016000, 44355068641175040, 2667095701669969920, 161021441731743129600, 9754428938330096713728, 592621128107578217201664
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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All solutions for n=1
.-1.-1...-1..2...-1..2...-1..2....2..2...-1..2...-1.-1....2..2...-1..2
.-1..2...-1.-1....2.-1....2..2...-1..2....2..2...-1.-1...-1..2...-1..2
.-1.-1...-1.-1....2..2....2.-1....2.-1...-1..2...-1..2...-1..2....2..2
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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