A213021 - OEIS

%I #8 Jun 06 2012 14:52:03

%S 1,2,2,2,2,3,7,9,2,19,13,21,25,10,22,60,2,5,11,25,9,41,11,14,53,21,

%T 141,54,137,79,30,1,2,51,16,5,8,9,39,5,10,74,11,3,61,25,69,32,104,129,

%U 44,48,151,243,19,165,7,96,20,93,130,136,98,25,102,156,74

%N Least k such that k*30^n+1 is prime

%H Pierre CAMI, <a href="/A213021/b213021.txt">Table of n, a(n) for n = 1..2000</a>

%t Table[k = 1; While[! PrimeQ[k*30^n + 1], k++]; k, {n, 100}] (* _T. D. Noe_, Jun 06 2012 *)

%o PFGW64 and SCRIPTIFY from Primeform Group

%o Command : pfgw64 -f in.txt

%o in.txt file :

%o SCRIPT

%o DIM nn,0

%o DIM kk

%o DIMS tt

%o OPENFILEOUT myfile,a(n).txt

%o LABEL loopn

%o SET nn,nn+1

%o IF nn>2000 THEN END

%o SET kk,0

%o LABEL loopk

%o SET kk,kk+1

%o SETS tt,%d,%d\,;nn;kk

%o PRP kk*30^nn+1,tt

%o IF ISPRP THEN GOTO b

%o IF ISPRIME THEN GOTO b

%o GOTO loopk

%o LABEL b

%o WRITE myfile,tt

%o GOTO loopn

%o (PARI)

%o a(n)=for(k=1,10^10,if(isprime(k*30^n+1),return(k)));

%o vector(66,n,a(n))

%o /* _Joerg Arndt_, Jun 03 2012 */

%K nonn

%O 1,2

%A _Pierre CAMI_, Jun 03 2012