A108632 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Complement of 108631 in the class of semiprimes.

LINKS

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

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 *)

CROSSREFS

Cf. A108631.