Numbers n such that tau(sigma(n))= tau(tau(n)).

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =16a(5) =18a(6) =25a(7) =50a(8) =64a(9) =144a(10) =289a(11) =576a(12) =578a(13) =729a(14) =1458a(15) =1600a(16) =1681a(17) =2401a(18) =2916a(19) =3362a(20) =3481a(21) =3600a(22) =4096a(23) =4624a(24) =4802a(25) =5041a(26) =6962a(27) =7921a(28) =9604a(29) =10082