Numbers k such that phi(k+1) = phi(k-1).

Terms

a(0) =5a(1) =8a(2) =9a(3) =11a(4) =27a(5) =33a(6) =71a(7) =75a(8) =123a(9) =147a(10) =309a(11) =315a(12) =387a(13) =513a(14) =555a(15) =573a(16) =627a(17) =636a(18) =729a(19) =795a(20) =843a(21) =911a(22) =915a(23) =1016a(24) =1083a(25) =1227a(26) =1323a(27) =1331a(28) =1347a(29) =1467