cp's OEIS Frontend

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).

%I A192707 #7 Jun 02 2025 04:13:25
%S A192707 2,6,17,39,85,167,309,546,919,1486,2338,3564,5300,7703,11016,15451,
%T A192707 21303,28978,38908,51626,67686,87827,112967,144076,182028,228322,
%U A192707 284414,351962,432504,528554,642212,776430,933563,1117263,1331217,1579771,1865945
%N 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).
%C A192707 Column (7,2,n) of A192710
%H A192707 R. H. Hardin, <a href="/A192707/b192707.txt">Table of n, a(n) for n = 1..163</a>
%e A192707 Some solutions for 7X2 <= 2*4^2
%e A192707 .-1..1...-3..3...-2..2...-3..3...-3..3...-2..2...-2..2...-2..2...-2..2...-2..2
%e A192707 .-1..1....0..0...-1..1...-1..1...-1..1...-1..1...-1..1....0..0...-2..2...-2..2
%e A192707 .-1..1....0..0...-1..1....0..0...-1..1...-1..1....0..0....0..0...-2..2....0..0
%e A192707 .-1..1....0..0...-1..1....0..0...-1..1...-1..1....0..0....0..0...-1..1....0..0
%e A192707 .-1..1....0..0....0..0....0..0...-1..1...-1..1....0..0....0..0...-1..1....0..0
%e A192707 .-1..1....0..0....0..0....0..0...-1..1...-1..1....0..0....0..0...-1..1....0..0
%e A192707 ..0..0....0..0....0..0....0..0....0..0...-1..1....0..0....0..0....0..0....0..0
%K A192707 nonn
%O A192707 1,1
%A A192707 _R. H. Hardin_ Jul 07 2011