a(n) = (1/phi(n)) * Sum_{j=1..n} Sum_{k=1..n} phi(n*j*k).

Terms

a(0) =1a(1) =9a(2) =26a(3) =83a(4) =132a(5) =404a(6) =400a(7) =989a(8) =1199a(9) =2382a(10) =2096a(11) =5381a(12) =3922a(13) =8358a(14) =8525a(15) =12897a(16) =10758a(17) =25517a(18) =16618a(19) =34116a(20) =30217a(21) =45156a(22) =34224a(23) =77503a(24) =50559a(25) =87512a(26) =77328a(27) =119162a(28) =84364a(29) =198907