

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 zerosum 2vectors 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
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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



