Primes p such that q = 4p^2 + 1, r = 4q^2 + 1 and s = 4r^2 + 1 are all primes.

Terms

a(0) =13a(1) =9833a(2) =41647a(3) =151607a(4) =264757a(5) =356123a(6) =361223a(7) =446863a(8) =449093a(9) =457813a(10) =531383a(11) =641057a(12) =655927a(13) =841697a(14) =855947a(15) =899263a(16) =913687a(17) =1052813a(18) =1081757a(19) =1379383a(20) =1506493a(21) =1575757a(22) =1685087a(23) =1821013a(24) =1821377a(25) =1981517a(26) =2054233a(27) =2142037