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A192709 Number of 9X2 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 9 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations) 1
2, 6, 19, 46, 108, 231, 460, 872, 1581, 2737, 4607, 7508, 11904, 18426, 27989, 41631, 60856, 87536, 124153, 173696, 239976, 327657, 442880, 592595, 785351, 1031659, 1344609, 1738831, 2232241, 2845802, 3605355, 4538949, 5681318, 7071215, 8756412 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column (9,2,n) of A192710

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..102

EXAMPLE

Some solutions for 9X2 <= 2*4^2

.-2..2...-3..3...-2..2...-2..2...-1..1...-2..2...-2..2....0..0...-3..3...-1..1

.-1..1...-2..2...-2..2...-2..2...-1..1...-1..1...-1..1....0..0...-2..2...-1..1

.-1..1...-1..1...-2..2...-2..2...-1..1...-1..1...-1..1....0..0...-1..1...-1..1

.-1..1...-1..1...-1..1...-1..1....0..0...-1..1...-1..1....0..0...-1..1...-1..1

.-1..1...-1..1....0..0...-1..1....0..0...-1..1...-1..1....0..0....0..0...-1..1

.-1..1....0..0....0..0...-1..1....0..0....0..0...-1..1....0..0....0..0...-1..1

.-1..1....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0...-1..1

..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0...-1..1

..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0...-1..1

CROSSREFS

Sequence in context: A273180 A280041 A058081 * A034533 A192711 A192712

Adjacent sequences:  A192706 A192707 A192708 * A192710 A192711 A192712

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 07 2011

STATUS

approved

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Last modified January 24 04:47 EST 2022. Contains 350534 sequences. (Running on oeis4.)