Numbers n such that phi(3n-1) = sigma(n).

Terms

a(0) =1a(1) =3a(2) =5a(3) =7a(4) =35a(5) =39a(6) =47a(7) =51a(8) =145a(9) =210a(10) =215a(11) =287a(12) =321a(13) =355a(14) =385a(15) =532a(16) =572a(17) =635a(18) =702a(19) =1248a(20) =1357a(21) =1566a(22) =1577a(23) =1720a(24) =1837a(25) =2241a(26) =2619a(27) =2635a(28) =2910a(29) =3243