A192714 Number of 13X2 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 13 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations)

2, 6, 19, 55, 140, 331, 732, 1533, 3055, 5857, 10824, 19386, 33743, 57293, 95044, 154445, 246197, 385697, 594416, 902641, 1351643, 1998191, 2918046, 4213843, 6019994, 8515367, 11930845, 16568416, 22815114, 31168260, 42253487, 56871045

Offset

1,1

Comments

Column (13,2,n) of A192710

Links

R. H. Hardin, Table of n, a(n) for n = 1..62

Example

Some solutions for 13X2 <= 2*4^2
.-3..3...-2..2...-2..2...-2..2...-2..2...-2..2...-3..3...-2..2...-2..2...-3..3
.-1..1....0..0...-2..2...-2..2...-2..2...-2..2...-1..1...-1..1...-1..1...-2..2
.-1..1....0..0...-1..1...-2..2...-2..2....0..0...-1..1...-1..1...-1..1...-1..1
.-1..1....0..0...-1..1...-1..1...-1..1....0..0...-1..1...-1..1...-1..1...-1..1
.-1..1....0..0...-1..1...-1..1...-1..1....0..0...-1..1...-1..1...-1..1....0..0
.-1..1....0..0...-1..1...-1..1....0..0....0..0...-1..1...-1..1...-1..1....0..0
.-1..1....0..0...-1..1...-1..1....0..0....0..0....0..0...-1..1...-1..1....0..0
..0..0....0..0...-1..1....0..0....0..0....0..0....0..0...-1..1...-1..1....0..0
..0..0....0..0...-1..1....0..0....0..0....0..0....0..0...-1..1....0..0....0..0
..0..0....0..0...-1..1....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....0..0....0..0....0..0
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0

Crossrefs

Sequence in context: A214948 A192713 A014559 * A027098 A183305 A192715

Adjacent sequences: A192711 A192712 A192713 * A192715 A192716 A192717

Keyword

nonn

Author

R. H. Hardin Jul 07 2011

Status

approved