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A192707
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)
1
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
OFFSET
1,1
COMMENTS
Column (7,2,n) of A192710
LINKS
EXAMPLE
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
CROSSREFS
Sequence in context: A204450 A037261 A239234 * A252814 A072077 A229732
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 07 2011
STATUS
approved