Number of ordered triples (i,j,k) with |i| + |j| + |k| <= n and gcd(i,j,k) <= 1.

Terms

a(0) =1a(1) =7a(2) =19a(3) =51a(4) =99a(5) =195a(6) =291a(7) =483a(8) =675a(9) =963a(10) =1251a(11) =1731a(12) =2115a(13) =2787a(14) =3363a(15) =4131a(16) =4899a(17) =6051a(18) =6915a(19) =8355a(20) =9507a(21) =11043a(22) =12483a(23) =14595a(24) =16131a(25) =18531a(26) =20547a(27) =23139a(28) =25443a(29) =28803