Quadruples of different integers from [ 1,n ] with no common factors between pairs.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =2a(6) =10a(7) =14a(8) =24a(9) =26a(10) =68a(11) =72a(12) =151a(13) =167a(14) =192a(15) =228a(16) =411a(17) =431a(18) =708a(19) =758a(20) =858a(21) =928a(22) =1419a(23) =1475a(24) =1874a(25) =2013a(26) =2353a(27) =2499a(28) =3515a(29) =3571