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)

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

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