Numbers n such that both phi(n) and psi(n) are perfect squares.

Terms

a(0) =1a(1) =60a(2) =170a(3) =240a(4) =315a(5) =540a(6) =679a(7) =680a(8) =960a(9) =1500a(10) =2142a(11) =2160a(12) =2720a(13) =2835a(14) =3840a(15) =4250a(16) =4365a(17) =4860a(18) =5770a(19) =6000a(20) =7875a(21) =8568a(22) =8640a(23) =9154a(24) =9809a(25) =10880a(26) =13500a(27) =14322a(28) =15360a(29) =15435