The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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. 3
 27361, 65731, 167623, 424093, 1559449, 2389693, 3880633, 4683661, 5755921, 5780881, 6124411, 6840643, 7802959, 7822879, 7917769, 8876719, 9488683, 9640321, 9966139, 10392073, 10865083, 10988743, 12363991, 12457681, 12756253, 13471561, 14437561, 14508709, 14550331, 14839711, 15366223, 16574143 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A prime p here is prime p(n) when A224611(n) = 1. A subsequence of A224614. - M. F. Hasler, Apr 22 2013 LINKS Pierre CAMI, Table of n, a(n) for n = 1..747 MATHEMATICA 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 *) 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 *) PROG (PFGW SCRIPT) SCRIPT DIM n, 1 DIM q DIMS t OPENFILEOUT myf, a(n).txt LABEL a SET n, n+1 SETS t, %d\,; p(n) SET q, 2*p(n)^3-1 PRP q, t IF ISPRP THEN GOTO b GOTO a LABEL b SET q, 2*p(n)*q^2-1 PRP q, t IF ISPRP THEN GOTO c GOTO a LABEL c SET q, 2*p(n)*q^2-1 PRP q, t IF ISPRP THEN GOTO d GOTO a LABEL d WRITE myf, t GOTO a CROSSREFS Cf. A224611, A224613, A224614. Sequence in context: A234686 A064967 A168215 * A237296 A166224 A187533 Adjacent sequences: A224623 A224624 A224625 * A224627 A224628 A224629 KEYWORD nonn AUTHOR Pierre CAMI, Apr 12 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 17 11:55 EDT 2024. Contains 371763 sequences. (Running on oeis4.)