Integers with only one prime factor and whose Euler's totient is a perfect biquadrate.

Terms

a(0) =2a(1) =17a(2) =32a(3) =257a(4) =512a(5) =1297a(6) =8192a(7) =65537a(8) =131072a(9) =160001a(10) =331777a(11) =614657a(12) =1336337a(13) =1419857a(14) =2097152a(15) =4477457a(16) =5308417a(17) =8503057a(18) =9834497a(19) =29986577a(20) =33554432a(21) =40960001a(22) =45212177a(23) =59969537a(24) =65610001a(25) =126247697a(26) =193877777a(27) =303595777a(28) =384160001a(29) =406586897