A192711 Number of 10 X 2 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 10 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).

2, 6, 19, 49, 118, 259, 534, 1042, 1941, 3465, 5996, 10040, 16364, 26012, 40522, 61835, 92657, 136556, 198316, 283977, 401349, 560438, 774140, 1058263, 1432174, 1920672, 2554179, 3369134, 4409927, 5730887, 7397192, 9486111, 12090252, 15318436

Offset: 1

Author

R. H. Hardin, Jul 07 2011

Keywords

• nonn

Comments

Column (10,2,n) of A192710.

Examples

			Some solutions for 10 X 2 <= 2*4^2
.-2..2...-3..3...-2..2...-1..1....0..0...-2..2...-3..3...-1..1...-3..3...-2..2
.-1..1...-2..2...-2..2...-1..1....0..0...-2..2...-2..2....0..0...-1..1...-1..1
.-1..1...-1..1...-2..2...-1..1....0..0...-2..2...-1..1....0..0....0..0...-1..1
.-1..1...-1..1...-1..1....0..0....0..0...-1..1....0..0....0..0....0..0...-1..1
..0..0...-1..1....0..0....0..0....0..0...-1..1....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....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
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..86

Crossrefs

Cf. A192710.