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A224627 Prime numbers p such that 2*p^3-1, 2*p*q^2-1, 2*p*r^2-1, and 2*p*s^2-1 are prime numbers. 0
19460899, 86276401, 87980803, 167646631, 300722029, 343507111, 479516311, 906597943, 998757829, 1031308249, 1112697199, 1311383431, 1962194053 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A224612, p = prime(n) when A224612(n)=1.

LINKS

Table of n, a(n) for n=1..13.

MATHEMATICA

Reap[ For[p = 2, p < 2*10^9, p = NextPrime[p], If[PrimeQ[q = 2*p^3 - 1] && PrimeQ[r = 2*p*q^2 - 1] && PrimeQ[s = 2*p*r^2 - 1] && PrimeQ[2*p*s^2 - 1], Print[p]; Sow[p]] ]][[2, 1]] (* Jean-François Alcover, Apr 22 2013 *)

PROG

(PFGW & SCRIPTIFY)

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

SET q, 2*p(n)*q^2-1

PRP q, t

IF ISPRP THEN GOTO e

GOTO a

LABEL e

WRITE t, myf

GOTO a

CROSSREFS

Cf. A224612, A224613, A224614, A224626.

Sequence in context: A184790 A183697 A022248 * A038683 A017287 A017395

Adjacent sequences:  A224624 A224625 A224626 * A224628 A224629 A224630

KEYWORD

nonn

AUTHOR

Pierre CAMI, Apr 12 2013

EXTENSIONS

More terms from Jean-François Alcover, Apr 22 2013

STATUS

approved

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Last modified April 20 14:27 EDT 2019. Contains 322310 sequences. (Running on oeis4.)