Numbers k such that phi(k)^2+sigma(k)^2 is prime.

Terms

a(0) =1a(1) =4a(2) =8a(3) =25a(4) =50a(5) =121a(6) =225a(7) =324a(8) =400a(9) =800a(10) =1024a(11) =1250a(12) =1681a(13) =1682a(14) =2025a(15) =2209a(16) =4761a(17) =5041a(18) =5625a(19) =6561a(20) =6724a(21) =7569a(22) =11449a(23) =17424a(24) =18225a(25) =18769a(26) =21609a(27) =26244a(28) =34969a(29) =36481