Number of ordered quadruples of integers from [ 1,n ] with no common factors between pairs.

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =12a(5) =14a(6) =28a(7) =36a(8) =52a(9) =58a(10) =110a(11) =118a(12) =209a(13) =231a(14) =264a(15) =308a(16) =507a(17) =533a(18) =828a(19) =886a(20) =998a(21) =1078a(22) =1591a(23) =1655a(24) =2074a(25) =2225a(26) =2583a(27) =2741a(28) =3785a(29) =3849