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%I #7 Feb 05 2013 05:27:24
%S 1,1,1,1,2,2,2,2,3,3,4,3,3,5,4,4,7,4,5,6,6,6,6,6,7,9,7,6,11,8,8,12,7,
%T 9,12,9,10,10,12,10,14,11,9,14,12,12,16,10,13,19,13,13,16,14,14,18,15,
%U 12,18,16,17,21,13,16,23,17,20,18,18,18,24,18,15,28,19,19,25
%N Number of 3-dimensional integer direction vectors (a,b,c) towards grid points at squared integer distance 2n-1 with a >= b >= c >= 0.
%C A vector is a direction vector if its nonzero components have their GCD = 1.
%e The 4 directions towards points at squared distance 29 (i.e. for n=15) are (signed permutations of) [ 24,16,3 ],[ 24,12,11 ],[ 21,20,0 ],[ 21,16,12 ]
%Y Cf. A049318, A049319.
%K nonn
%O 1,5
%A _Wouter Meeussen_
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