A091296 - OEIS

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

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OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..55.

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 *)

Select[Range[1000], PrimeOmega[#]==2 && And@@OddQ[IntegerDigits[#]]&] (* Harvey P. Dale, Jul 12 2011 *)

CROSSREFS

Cf. A001358 (semiprimes), A108636.

Sequence in context: A320062 A062016 A108637 * A107076 A155775 A228096

Adjacent sequences: A091293 A091294 A091295 * A091297 A091298 A091299

KEYWORD

easy,nonn,base

AUTHOR

Zak Seidov, Feb 22 2004

EXTENSIONS

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

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

STATUS

approved