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A225747 a(n) = smallest prime q > a(n-1) such that 2*prime(n)*q^prime(n)+1 is also prime. 1
2, 3, 7, 17, 1579, 1997, 2347, 3323, 6637, 11161, 13829, 18287, 40759, 42197, 42337, 45757, 46141, 48383, 49253, 51631, 52541, 53549, 73477, 78079, 81677, 111439, 164363, 166567, 170441, 180667, 191507, 202729, 209029, 257351, 292471, 294809, 300569, 328787 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Pierre CAMI, Table of n, a(n) for n = 1..177

EXAMPLE

2*2*2^2+1=17 prime so a(1)=2,

2*3*2^3+1=49 composite,

2*3*3^3+1=163 prime so a(2)=3 as 3>2.

PROG

(PFGW & SCRIPTIFY)

SCRIPT

DIM n, 0

DIM k, 0

DIM q

DIMS t

OPENFILEOUT myfile, a(n).txt

LABEL a

SET n, n+1

IF n>177 THEN END

LABEL b

SET k, k+1

SET q, p(k)

SETS t, %d\,; q

PRP 2*p(n)*q^p(n)+1, t

IF ISPRP THEN GOTO c

GOTO b

LABEL c

WRITE myfile, q

GOTO a

CROSSREFS

Cf. A225403.

Sequence in context: A102226 A195530 A295509 * A058334 A303090 A131093

Adjacent sequences:  A225744 A225745 A225746 * A225748 A225749 A225750

KEYWORD

nonn

AUTHOR

Pierre CAMI, May 14 2013

STATUS

approved

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Last modified January 18 05:09 EST 2020. Contains 330995 sequences. (Running on oeis4.)