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

Terms

a(0) =1a(1) =3a(2) =9a(3) =18a(4) =43a(5) =62a(6) =125a(7) =181a(8) =282a(9) =370a(10) =597a(11) =725a(12) =1090a(13) =1336a(14) =1709a(15) =2085a(16) =2873a(17) =3280a(18) =4366a(19) =5018a(20) =6054a(21) =6966a(22) =8854a(23) =9790a(24) =11943a(25) =13451a(26) =15744a(27) =17530a(28) =21237a(29) =22839