Search: id:A118690
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%I A118690
%S A118690 4,6,9,22,33,55,77,91,123,141,177,213,217,321,411,717,721,771,1135,1157,
%T A118690 1315,1351,1513,1517,1751,3151,5131,5311,7115,11157,11215,11521,11611,
%U A118690 11751,12115,12151,15117,15711,17151,21151,51211,57111,61111,75111
%N A118690 Semiprimes for which both the sum and the product of the digits is also 
               a semiprime.
%e A118690 91 is in the sequence because (1) it is a semiprime, (2) the sum of its 
               digits is 9+1=10, (3) the product of its digits is 1*9=9 and (4) 
               both 9 and 10 are semiprimes.
%t A118690 spQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; fQ[n_] := Block[{id 
               = IntegerDigits@n}, spQ@n && spQ[Plus @@ id] && spQ[Times @@ id]]; 
               Select[ Range@111172, fQ@# &] - Robert G. Wilson v (rgwv(AT)rgwv.com), 
               Jun 15 2006
%Y A118690 Cf. A001358.
%Y A118690 Sequence in context: A137253 A035135 A046338 this_sequence A084994 A046328 
               A046376
%Y A118690 Adjacent sequences: A118687 A118688 A118689 this_sequence A118691 A118692 
               A118693
%K A118690 base,nonn
%O A118690 1,1
%A A118690 Luc Stevens (lms022(AT)yahoo.com), May 20 2006
%E A118690 More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 15 2006

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