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A213021 Least k such that k*30^n+1 is prime 1
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, 141, 54, 137, 79, 30, 1, 2, 51, 16, 5, 8, 9, 39, 5, 10, 74, 11, 3, 61, 25, 69, 32, 104, 129, 44, 48, 151, 243, 19, 165, 7, 96, 20, 93, 130, 136, 98, 25, 102, 156, 74 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Pierre CAMI, Table of n, a(n) for n = 1..2000

MATHEMATICA

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

PROG

PFGW64 and SCRIPTIFY from Primeform Group

Command : pfgw64 -f in.txt

in.txt file :

SCRIPT

DIM nn, 0

DIM kk

DIMS tt

OPENFILEOUT myfile, a(n).txt

LABEL loopn

SET nn, nn+1

IF nn>2000 THEN END

SET kk, 0

LABEL loopk

SET kk, kk+1

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

PRP kk*30^nn+1, tt

IF ISPRP THEN GOTO b

IF ISPRIME THEN GOTO b

GOTO loopk

LABEL b

WRITE myfile, tt

GOTO loopn

(PARI)

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

vector(66, n, a(n))

/* Joerg Arndt, Jun 03 2012 */

CROSSREFS

Sequence in context: A138705 A319187 A248780 * A078228 A119762 A153667

Adjacent sequences:  A213018 A213019 A213020 * A213022 A213023 A213024

KEYWORD

nonn

AUTHOR

Pierre CAMI, Jun 03 2012

STATUS

approved

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Last modified July 18 15:44 EDT 2019. Contains 325144 sequences. (Running on oeis4.)