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

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =5a(5) =12a(6) =31a(7) =53a(8) =99a(9) =148a(10) =257a(11) =335a(12) =531a(13) =690a(14) =948a(15) =1192a(16) =1685a(17) =1977a(18) =2689a(19) =3171a(20) =3961a(21) =4651a(22) =5987a(23) =6716a(24) =8353a(25) =9539a(26) =11340a(27) =12781a(28) =15599a(29) =16945