Numbers k such that k = phi(sigma(phi(sigma(k)))).

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =8a(5) =12a(6) =48a(7) =60a(8) =72a(9) =96a(10) =128a(11) =240a(12) =432a(13) =480a(14) =720a(15) =1728a(16) =2016a(17) =6912a(18) =10368a(19) =14080a(20) =32768a(21) =142560a(22) =184320a(23) =196560a(24) =712800a(25) =1140480a(26) =1190400a(27) =1658880a(28) =1801800a(29) =3345408