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A020457 Primes that contain digits 1 and 9 only. 7

%I

%S 11,19,191,199,911,919,991,1999,9199,11119,19919,19991,91199,99119,

%T 99191,99991,111119,111191,111919,119191,191119,191911,191999,199999,

%U 911111,919111,991999,999199,1111991,1191119,1191191,1191199,1191991,1199999

%N Primes that contain digits 1 and 9 only.

%H Vincenzo Librandi, <a href="/A020457/b020457.txt">Table of n, a(n) for n = 1..1000</a>

%t Flatten[Table[Select[FromDigits/@Tuples[{1,9},n],PrimeQ],{n,7}]] (* _Vincenzo Librandi_, Jul 27 2012 *)

%o (MAGMA) [p: p in PrimesUpTo(1199999) | Set(Intseq(p)) subset [1, 9]]; // _Vincenzo Librandi_, Jul 27 2012

%K nonn,base

%O 1,1

%A _David W. Wilson_

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Last modified May 25 01:23 EDT 2019. Contains 323534 sequences. (Running on oeis4.)