Number of numbers which require n iterations of the unitary totient function (A047994) to reach 1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =21a(6) =38a(7) =82a(8) =164a(9) =261a(10) =424a(11) =749a(12) =1097a(13) =1721a(14) =2592a(15) =4351a(16) =7319a(17) =10725a(18) =17013a(19) =27773a(20) =44767a(21) =73914a(22) =118990a(23) =185059a(24) =275055a(25) =401059a(26) =617679a(27) =935331a(28) =1379826a(29) =2089569