login
Primes that contain digits 7 and 8 only.
6

%I #12 Sep 08 2022 08:44:45

%S 7,787,877,887,7877,8887,78787,78877,78887,87877,87887,777787,777877,

%T 778777,787777,878777,888887,7778777,7788787,7877777,7878877,7878887,

%U 7888877,8787887,8788777,8877787,8887777,77778887,77787887,77877887

%N Primes that contain digits 7 and 8 only.

%H Vincenzo Librandi, <a href="/A020470/b020470.txt">Table of n, a(n) for n = 1..1000</a>

%t Flatten[Table[Select[FromDigits/@Tuples[{7,8},n],PrimeQ],{n,8}]] (* _Vincenzo Librandi_, Jul 28 2012 *)

%o (Magma) [p: p in PrimesUpTo(77877887) | Set(Intseq(p)) subset [7,8]]; // _Vincenzo Librandi_, Jul 28 2012

%K nonn,base

%O 1,1

%A _David W. Wilson_