Euler phi function applied to the cubefull exponentially odd numbers (A335988).

Terms

a(0) =1a(1) =4a(2) =18a(3) =16a(4) =100a(5) =64a(6) =72a(7) =162a(8) =294a(9) =256a(10) =288a(11) =400a(12) =1210a(13) =648a(14) =1024a(15) =1458a(16) =2028a(17) =1176a(18) =2500a(19) =1800a(20) =1152a(21) =1600a(22) =4624a(23) =6498a(24) =2592a(25) =4096a(26) =5292a(27) =4840a(28) =4704a(29) =11638