Numbers k such that sigma(sigma(k)) == phi(k) (mod sigma(k)).

Terms

a(0) =2a(1) =26a(2) =77a(3) =85a(4) =194a(5) =335a(6) =707a(7) =1350a(8) =2443a(9) =2639a(10) =9158a(11) =9602a(12) =15238a(13) =16625a(14) =19698a(15) =23199a(16) =24416a(17) =52328a(18) =54663a(19) =56927a(20) =64206a(21) =67226a(22) =69875a(23) =82235a(24) =100837a(25) =104489a(26) =136213a(27) =150040a(28) =161268a(29) =230216