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A192707
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Number of 7X2 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 7 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations)
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1
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2, 6, 17, 39, 85, 167, 309, 546, 919, 1486, 2338, 3564, 5300, 7703, 11016, 15451, 21303, 28978, 38908, 51626, 67686, 87827, 112967, 144076, 182028, 228322, 284414, 351962, 432504, 528554, 642212, 776430, 933563, 1117263, 1331217, 1579771, 1865945
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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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Some solutions for 7X2 <= 2*4^2
.-1..1...-3..3...-2..2...-3..3...-3..3...-2..2...-2..2...-2..2...-2..2...-2..2
.-1..1....0..0...-1..1...-1..1...-1..1...-1..1...-1..1....0..0...-2..2...-2..2
.-1..1....0..0...-1..1....0..0...-1..1...-1..1....0..0....0..0...-2..2....0..0
.-1..1....0..0...-1..1....0..0...-1..1...-1..1....0..0....0..0...-1..1....0..0
.-1..1....0..0....0..0....0..0...-1..1...-1..1....0..0....0..0...-1..1....0..0
.-1..1....0..0....0..0....0..0...-1..1...-1..1....0..0....0..0...-1..1....0..0
..0..0....0..0....0..0....0..0....0..0...-1..1....0..0....0..0....0..0....0..0
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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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