A192703 - OEIS

A192703

Number of 4X2 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 4 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations)

2, 6, 12, 23, 41, 70, 106, 159, 230, 323, 436, 578, 757, 975, 1232, 1536, 1889, 2317, 2797, 3355, 3994, 4711, 5523, 6438, 7465, 8618, 9888, 11296, 12839, 14557, 16398, 18449, 20689, 23115, 25758, 28591, 31673, 34995, 38586, 42415, 46528, 50984, 55687

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OFFSET

1,1

COMMENTS

Column (4,2,n) of A192710

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

EXAMPLE

Some solutions for 4X2 <= 2*4^2

.-3..3...-3..3...-1..1...-2..2...-3..3...-2..2...-2..2...-1..1...-1..1...-2..2

..0..0...-1..1...-1..1...-2..2...-2..2...-2..2....0..0...-1..1...-1..1...-2..2

..0..0...-1..1....0..0....0..0...-1..1...-2..2....0..0...-1..1...-1..1...-2..2