Beginnings of maximal chains of primes with four members (three links).

Terms

a(0) =13a(1) =89a(2) =809a(3) =4561a(4) =6689a(5) =7603a(6) =11321a(7) =16493a(8) =18229a(9) =22153a(10) =24107a(11) =28409a(12) =28687a(13) =29153a(14) =32749a(15) =33013a(16) =54493a(17) =55663a(18) =63337a(19) =63419a(20) =67169a(21) =86011a(22) =90289a(23) =108881a(24) =113647a(25) =116929a(26) =132589a(27) =133187a(28) =136033a(29) =136403