%I #22 Sep 08 2022 08:44:45
%S 2,7,227,277,727,2777,7727,22277,22727,22777,27277,72227,72277,72727,
%T 272227,272777,727777,777277,2227727,2227777,2272727,2277727,2727727,
%U 2772227,7272227,7722277,7727777,7772777,7777727,22227277,22272277
%N Primes that contain digits 2 and 7 only.
%H Alois P. Heinz, <a href="/A020459/b020459.txt">Table of n, a(n) for n = 1..20000</a> (first 1000 terms from Vincenzo Librandi)
%H James Maynard and Brady Haran, <a href="https://www.youtube.com/watch?v=eeoBCS7IEqs">Primes without a 7</a>, Numberphile video (2019)
%t Flatten[Table[Select[FromDigits/@Tuples[{2,7},n],PrimeQ],{n,8}]] (* _Vincenzo Librandi_, Jul 27 2012 *)
%o (Magma) [p: p in PrimesUpTo(22272277) | Set(Intseq(p)) subset [2, 7]]; // _Vincenzo Librandi_, Jul 27 2012
%Y Cf. A000040, A284921, A329760.
%K nonn,base
%O 1,1
%A _David W. Wilson_
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