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

Terms

a(0) =1a(1) =8a(2) =9a(3) =32a(4) =36a(5) =50a(6) =100a(7) =225a(8) =242a(9) =484a(10) =512a(11) =578a(12) =729a(13) =800a(14) =900a(15) =1089a(16) =1156a(17) =1250a(18) =1936a(19) =2025a(20) =2048a(21) =2304a(22) =2312a(23) =2601a(24) =2916a(25) =3025a(26) =3872a(27) =4418a(28) =6400a(29) =7225