Nonsquarefree "year numbers" (numbers n such that phi(n) = 2*phi(sigma(n)): A137815).

Terms

a(0) =5491a(1) =8075a(2) =25317a(3) =27455a(4) =71383a(5) =72283a(6) =76131a(7) =104975a(8) =138575a(9) =193041a(10) =203167a(11) =295569a(12) =295947a(13) =298775a(14) =334951a(15) =356915a(16) =361415a(17) =400843a(18) =451535a(19) =492275a(20) =509575a(21) =572975a(22) =589475a(23) =595975a(24) =654493a(25) =683757a(26) =815975a(27) =862087a(28) =876627a(29) =919075