Number of ordered quadruples of integers from [ 1..n ] with no global factor.

Terms

a(0) =1a(1) =4a(2) =13a(3) =29a(4) =63a(5) =106a(6) =189a(7) =289a(8) =444a(9) =626a(10) =911a(11) =1203a(12) =1657a(13) =2130a(14) =2766a(15) =3462a(16) =4430a(17) =5359a(18) =6688a(19) =7992a(20) =9670a(21) =11405a(22) =13704a(23) =15840a(24) =18730a(25) =21548a(26) =25037a(27) =28521a(28) =33015a(29) =37067