A091296 Semiprimes with odd digits.

9, 15, 33, 35, 39, 51, 55, 57, 77, 91, 93, 95, 111, 115, 119, 133, 155, 159, 177, 319, 335, 339, 355, 371, 377, 391, 393, 395, 511, 515, 517, 519, 533, 535, 537, 551, 553, 559, 573, 579, 591, 597, 713, 717, 731, 737, 753, 755, 771, 779, 791, 793, 799, 913, 917

Offset: 1

Author

Zak Seidov, Feb 22 2004

Keywords

• easy
• nonn
• base

Comments

Semiprimes with odd digits are more numerous than those with even digits, cf. A108636.

Links

• Mia Boudreau, Table of n, a(n) for n = 1..1000

Crossrefs

Intersection of A001358 and A014261.

Cf. A030096, A108636.

Programs

Mathematica

Select[Range[1000], Plus@@Last/@FactorInteger[ # ]==2&&Union[OddQ/@IntegerDigits[ # ]]=={True}&]
PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[ Table[ #[[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[ 938], PrimeFactorExponentsAdded[ # ] == 2 && Union[ OddQ /@ IntegerDigits[ # ]] == {True} &] (* Robert G. Wilson v, Feb 25 2004 *)
Select[Range[1000], PrimeOmega[#]==2 && And@@OddQ[IntegerDigits[#]]&] (* Harvey P. Dale, Jul 12 2011 *)

Extensions

Corrected and extended by Ray Chandler and Robert G. Wilson v, Feb 25 2004

Edited by N. J. A. Sloane, Apr 20 2007