A214700 - OEIS

A214700

Numbers n such that 9^n + 3^(n+1) - 1 is prime.

1, 2, 3, 4, 8, 21, 22, 31, 45, 86, 99, 127, 239, 264, 332, 338, 752, 793, 2310, 4364, 7454, 14788, 20031

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OFFSET

1,2

COMMENTS

no more n<30000

A214700(n) = i when A214730(i)=3

LINKS

PROG

PFGW and SCRIPTIFY

SCRIPT

DIM nn, 0

DIMS tt

OPENFILEOUT myfile, a(n)

LABEL loopn

SET nn, nn+1

IF nn>30000 THEN END

SETS tt, %d\ ; nn

PRP (3^nn+3)*3^nn-1, tt

IF ISPRP THEN GOTO a

IF ISPRIME THEN GOTO a

GOTO loopn

LABEL a

WRITE myfile, tt

GOTO loopn

(PARI) is(n)=ispseudoprime(9^n+3^(n+1)-1) \\ Charles R Greathouse IV, Jun 06 2017

CROSSREFS

KEYWORD

nonn

AUTHOR

Pierre CAMI, Jul 26 2012

STATUS

approved