OFFSET
1,1
COMMENTS
Let V = (b(1), b(2), ..., b(k)), where k > 1 and b(i) are distinct integers > 1 for j = 1..k. Call p a V-prime if the digits of p in base b(1) spell a prime in each of the bases b(2), ..., b(k).
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..1000
EXAMPLE
Consider the number a(2) = 173:
in base 2, a(2) = 10101101, which is the prime 172;
in base 3, 10101101 is the prime 2467;
in base 5, 10101101 is the prime 81401;
in base 7, 10101101 is the prime 840743
MATHEMATICA
{b1, b2, b3, b4} = {2, 3, 5, 7}; z = 15000;
u = Select[Prime[Range[z]],
PrimeQ[FromDigits[IntegerDigits[#, b1], b2]] &&
PrimeQ[FromDigits[IntegerDigits[#, b1], b3]] &&
PrimeQ[FromDigits[IntegerDigits[#, b1], b4]] &]
(* Peter J. C. Moses, Sep 27 2015 *)
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
Clark Kimberling, Oct 02 2015
STATUS
approved