cp's OEIS Frontend

A192691 Number of 1X4 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 1 zero-sum 4-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).

%I A192691 #8 Jun 02 2025 04:12:01
%S A192691 2,6,15,26,45,72,105,150,206,273,353,446,560,687,834,998,1182,1388,
%T A192691 1618,1875,2156,2463,2797,3151,3551,3978,4434,4923,5448,6009,6604,
%U A192691 7243,7925,8639,9404,10198,11051,11943,12887,13873,14909,16001,17135,18332,19584
%N A192691 Number of 1X4 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 1 zero-sum 4-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).
%C A192691 Column (1,4,n) of A192710
%H A192691 R. H. Hardin, <a href="/A192691/b192691.txt">Table of n, a(n) for n = 1..200</a>
%e A192691 Some solutions for 1X4 <= 2*4^2
%e A192691 .-1..0..0..1...-2..0..0..2...-1.-1.-1..3...-2..0..1..1...-3.-1..0..4
%K A192691 nonn
%O A192691 1,1
%A A192691 _R. H. Hardin_ Jul 07 2011