OFFSET
1,1
COMMENTS
This sequence is part of a two-dimensional array of sequences, given in the LINK, based on this same idea for any two different bases b, c > 1. Sequence A235265 and A235266 are the most elementary ones in this list. Sequences A089971, A089981 and A090707 through A090721, and sequences A065720 - A065727, follow the same idea with one base equal to 10.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
17 = 25_6 and 25_7 = 19 are both prime.
MATHEMATICA
Select[Prime[Range[300]], PrimeQ[FromDigits[IntegerDigits[#, 6], 7]]&] (* Harvey P. Dale, Sep 17 2017 *)
PROG
(PARI) is(p, b=7, c=6)=isprime(vector(#d=digits(p, c), i, b^(#d-i))*d~)&&isprime(p) \\ Note: This code is only valid for b > c.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
M. F. Hasler, Jan 13 2014
STATUS
approved