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%I #6 Feb 24 2013 18:26:13
%S 15,22,26,33,38,39,49,51,55,57,74,77,115,123,129,134,145,155,161,169,
%T 178,187,202,206,213,214,221,237,254,265,274,278,291,299,301,303,309,
%U 321,327,335,361,371,377,381,382,386,411,437,445,466,478,485,497,505
%N Semiprime plus its digits is semiprime.
%C Surprisingly there are only three(?) semiprimes sp, 10,14,15, such that sp minus its digits is semiprime.
%e 15=3*5 and 15+1+5=21=3*7.
%t Select[Range[500], Plus@@Last/@FactorInteger[ # ]==Plus@@Last/@FactorInteger[ #+Plus@@IntegerDigits[ # ]]==2&]
%K nonn,base
%O 1,1
%A _Zak Seidov_, Jun 14 2005
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