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A225724 Smallest prime q such that 2*prime(n)*q^prime(n)-1 is also prime. 1

%I #14 May 14 2013 14:03:50

%S 2,5,43,1409,19,107,31,653,521,1033,661,479,787,2063,1307,5477,1471,

%T 823,1163,1489,6991,9437,1019,6073,17,2089,9413,79,3137,12781,13049,

%U 3803,10789,3,1321,61,7,1187,1733,7151,1327,26111,487,3011,31,9343,89653,15377,283,21929

%N Smallest prime q such that 2*prime(n)*q^prime(n)-1 is also prime.

%H Pierre CAMI, <a href="/A225724/b225724.txt">Table of n, a(n) for n = 2..250</a>

%o ( PFGW & SCRIPTIFY )

%o SCRIPT

%o DIM n, 1

%o DIM k

%o DIM q

%o DIM pp

%o DIMS t

%o OPENFILEOUT myfile, a(n).txt

%o LABEL a

%o SET n, n+1

%o IF n>250 THEN END

%o SET k, 0

%o LABEL b

%o SET k, k+1

%o SET q, p(k)

%o SETS t, %d, %d\,; n; q

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

%o PRP pp, t

%o IF ISPRP THEN GOTO c

%o GOTO b

%o LABEL c

%o WRITE myfile, t

%o GOTO a

%Y Cf. A225403.

%K nonn

%O 2,1

%A _Pierre CAMI_, May 13 2013

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Last modified February 23 13:42 EST 2024. Contains 370283 sequences. (Running on oeis4.)