A213021 Least k such that k*30^n+1 is prime

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

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: A333528 A319187 A248780 * A078228 A119762 A153667

Adjacent sequences: A213018 A213019 A213020 * A213022 A213023 A213024

Keyword

nonn

Author

Pierre CAMI, Jun 03 2012

Status

approved