Numbers n such that lcm(sigma(n),phi(n)) is a perfect square.

Terms

a(0) =1a(1) =3a(2) =10a(3) =17a(4) =70a(5) =170a(6) =210a(7) =357a(8) =364a(9) =416a(10) =456a(11) =577a(12) =679a(13) =1092a(14) =1154a(15) =1358a(16) =1672a(17) =1705a(18) =1820a(19) =2280a(20) =2387a(21) =2565a(22) =2652a(23) =2835a(24) =2885a(25) =2910a(26) =3395a(27) =3570a(28) =4212a(29) =4577