Primes p = 1 mod 6 such that all three iterations p=(6p+1) give primes = 1 mod 6.

Terms

a(0) =61a(1) =6361a(2) =10771a(3) =11311a(4) =17791a(5) =19471a(6) =20011a(7) =24391a(8) =25951a(9) =30091a(10) =35251a(11) =41911a(12) =45631a(13) =47431a(14) =58711a(15) =67891a(16) =72271a(17) =74161a(18) =86341a(19) =89821a(20) =91711a(21) =93001a(22) =95311a(23) =103171a(24) =109321a(25) =124021a(26) =124171a(27) =132961a(28) =149491a(29) =153871