cp's OEIS Frontend

A262728 (2,3,5,7)-primes (see comments for precise definition).

%I A262728 #11 Nov 07 2015 06:31:44
%S A262728 2,173,181,233,443,877,967,1373,1831,4001,4231,4663,8191,8753,9043,
%T A262728 10333,10631,13537,14591,16931,18211,25411,32707,32843,33637,37573,
%U A262728 54773,56167,63853,64513,78101,84131,100207,102667,106087,112571,113153,133087,149531
%N A262728 (2,3,5,7)-primes (see comments for precise definition).
%C A262728 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).
%H A262728 Clark Kimberling, <a href="/A262728/b262728.txt">Table of n, a(n) for n = 1..1000</a>
%e A262728 Consider the number a(2) = 173:
%e A262728 in base 2, a(2) = 10101101, which is the prime 172;
%e A262728 in base 3, 10101101 is the prime 2467;
%e A262728 in base 5, 10101101 is the prime 81401;
%e A262728 in base 7, 10101101 is the prime 840743
%t A262728 {b1, b2, b3, b4} = {2, 3, 5, 7}; z = 15000;
%t A262728 u = Select[Prime[Range[z]],
%t A262728 PrimeQ[FromDigits[IntegerDigits[#, b1], b2]] &&
%t A262728 PrimeQ[FromDigits[IntegerDigits[#, b1], b3]] &&
%t A262728 PrimeQ[FromDigits[IntegerDigits[#, b1], b4]] &]
%t A262728 (* _Peter J. C. Moses_, Sep 27 2015 *)
%Y A262728 Cf. A000040, A262729.
%K A262728 nonn,easy,base
%O A262728 1,1
%A A262728 _Clark Kimberling_, Oct 02 2015