A108632 Semiprimes with prime digits (only digits 2,3,5,7 in semiprimes).

22, 25, 33, 35, 55, 57, 77, 235, 237, 253, 323, 327, 335, 355, 377, 527, 533, 535, 537, 553, 573, 723, 737, 753, 755, 2227, 2253, 2257, 2323, 2327, 2335, 2353, 2533, 2537, 2573, 2577, 2722, 2723, 2733, 2735, 2757, 2773, 3223, 3227, 3233, 3235, 3273, 3277

Offset: 1

Author

Zak Seidov, Jun 13 2005

Keywords

• nonn
• base

Comments

Complement of 108631 in the class of semiprimes.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A108631.

Programs

Mathematica

fQ[n_]:=Plus@@Last/@FactorInteger[n]==2&&Union[{2, 3, 5, 7}, IntegerDigits[n]]=={2, 3, 5, 7};Select[Range[4000], fQ[ # ]&]
Select[FromDigits/@Flatten[Table[Tuples[{2,3,5,7},n],{n,2,4}],1],PrimeOmega[#]==2&] (* Harvey P. Dale, Oct 19 2012 *)