cp's OEIS Frontend

A224626 Primes p such that q=2*p^3-1, r=2*p*q^2-1, and s=2*p*r^2-1 are all prime.

%I A224626 #29 Nov 27 2013 08:13:32
%S A224626 27361,65731,167623,424093,1559449,2389693,3880633,4683661,5755921,
%T A224626 5780881,6124411,6840643,7802959,7822879,7917769,8876719,9488683,
%U A224626 9640321,9966139,10392073,10865083,10988743,12363991,12457681,12756253,13471561,14437561,14508709,14550331,14839711,15366223,16574143
%N A224626 Primes p such that q=2*p^3-1, r=2*p*q^2-1, and s=2*p*r^2-1 are all prime.
%C A224626 A prime p here is prime p(n) when A224611(n) = 1.
%C A224626 A subsequence of A224614. - _M. F. Hasler_, Apr 22 2013
%H A224626 Pierre CAMI, <a href="/A224626/b224626.txt">Table of n, a(n) for n = 1..747</a>
%t A224626 Reap[ For[p = 2, p < 2*10^7, p = NextPrime[p], If[PrimeQ[q = 2*p^3 - 1] && PrimeQ[r = 2*p*q^2 - 1] && PrimeQ[2*p*r^2 - 1], Print[p]; Sow[p]] ]][[2, 1]] (* _Jean-François Alcover_, Apr 22 2013 *)
%t A224626 apQ[n_]:=Module[{q=2n^3-1,r},r=2n q^2-1;And@@PrimeQ[{q,r,2n r^2-1}]]; Select[ Prime[Range[1100000]],apQ] (* _Harvey P. Dale_, Nov 24 2013 *)
%o A224626 (PFGW SCRIPT)
%o A224626 SCRIPT
%o A224626 DIM n, 1
%o A224626 DIM q
%o A224626 DIMS t
%o A224626 OPENFILEOUT myf, a(n).txt
%o A224626 LABEL a
%o A224626 SET n, n+1
%o A224626 SETS t, %d\,; p(n)
%o A224626 SET q, 2*p(n)^3-1
%o A224626 PRP q, t
%o A224626 IF ISPRP THEN GOTO b
%o A224626 GOTO a
%o A224626 LABEL b
%o A224626 SET q, 2*p(n)*q^2-1
%o A224626 PRP q, t
%o A224626 IF ISPRP THEN GOTO c
%o A224626 GOTO a
%o A224626 LABEL c
%o A224626 SET q, 2*p(n)*q^2-1
%o A224626 PRP q, t
%o A224626 IF ISPRP THEN GOTO d
%o A224626 GOTO a
%o A224626 LABEL d
%o A224626 WRITE myf,t
%o A224626 GOTO a
%Y A224626 Cf. A224611, A224613, A224614.
%K A224626 nonn
%O A224626 1,1
%A A224626 _Pierre CAMI_, Apr 12 2013