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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column (7,2,n) of A192710

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..163

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

Adjacent sequences:  A192704 A192705 A192706 * A192708 A192709 A192710

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 07 2011

STATUS

approved

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Last modified December 4 10:59 EST 2021. Contains 349486 sequences. (Running on oeis4.)