Primes p such that b=2*p+1 is semiprime, c=2*b+1 is 3-almost prime and d=2*c+1 is 4-almost prime.

Terms

a(0) =43a(1) =1429a(2) =2239a(3) =3319a(4) =4831a(5) =6379a(6) =8821a(7) =10501a(8) =11383a(9) =12781a(10) =13003a(11) =14771a(12) =15091a(13) =16063a(14) =16759a(15) =18223a(16) =19213a(17) =19681a(18) =20021a(19) =22571a(20) =24103a(21) =24109a(22) =24571a(23) =25939a(24) =27271a(25) =28933a(26) =29833a(27) =30241a(28) =31723a(29) =33679