A155088 Numbers n such that n and prime(n) contain prime digits only.
2, 3, 55, 332, 352, 375, 733, 3573, 3575, 7235, 22222, 22223, 22322, 252323, 252335, 253777, 255225, 372755, 372772, 522532, 523255, 525737, 2275325, 2275327, 2275337, 2277333, 2277337, 3325772, 27727257, 27727277, 27727732, 27737332, 27737722, 27737723
Offset: 1
Examples
352 is in the sequence since 352 and prime(352) = 2377 use only prime digits (2, 3, 5, 7). For more examples see Links.
Links
- Giovanni Resta, Table of n, a(n) for n = 1..200
- Giovanni Resta, Table of a(n), prime(a(n)) for n = 1..200
Programs
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Mathematica
pQ[n_] := Union[IntegerDigits@n, {2,3,5,7}] == {2,3,5,7}; Select[Range[10^5], pQ@# && pQ@Prime@# &] (* Giovanni Resta, Mar 11 2013 *) Select[Flatten[Table[FromDigits/@Tuples[{2,3,5,7},n],{n,8}]],AllTrue[ IntegerDigits[Prime[#]],PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jun 24 2015 *)
Extensions
Corrected (332, 352, 375 inserted) by R. J. Mathar, May 05 2010
a(11)-a(34) from Giovanni Resta, Mar 11 2013
Comments