Number of ordered quadruples of integers from [ 2,n ] with no common factors between triples.

Terms

a(0) =0a(1) =1a(2) =3a(3) =14a(4) =20a(5) =56a(6) =86a(7) =148a(8) =198a(9) =360a(10) =438a(11) =713a(12) =884a(13) =1157a(14) =1433a(15) =2069a(16) =2365a(17) =3262a(18) =3766a(19) =4604a(20) =5331a(21) =6944a(22) =7684a(23) =9527a(24) =10777a(25) =12737a(26) =14229a(27) =17502a(28) =18812a(29) =22809