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)

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

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