Numbers k such that k + sigma(k) + sigma(sigma(k)) is a fourth power.

Terms

a(0) =19a(1) =1873a(2) =147497a(3) =792736a(4) =4551733a(5) =4967176a(6) =7333813a(7) =8539521a(8) =8674128a(9) =12388853a(10) =12948373a(11) =18331664a(12) =24834369a(13) =36294936a(14) =50952310a(15) =116340016a(16) =170434387a(17) =196966352a(18) =222505713a(19) =236504256a(20) =286766145a(21) =390771936a(22) =426323088a(23) =532998481a(24) =778930925a(25) =805653001