Search: id:A098146
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%I A098146
%S A098146 9,15,111,1003,10001,100001,1000001,10000001,100000001,1000000013,
%T A098146 10000000003,100000000007,1000000000007,10000000000015,100000000000013,
%U A098146 1000000000000003,10000000000000003,100000000000000015
%N A098146 First odd semiprime > 10^n.
%H A098146 Dario Alpern, <a href="http://www.alpertron.com.ar/ECM.HTM">Factorization 
               using the Elliptic Curve Method.</a>
%e A098146 a(0)=9 because 9=3*3 is the first odd semiprime following 10^0=1, a(13)=10000000000015=5*2000000000003.
%o A098146 (PARI) print1(9,",");for(n=1,10,forstep(i=10^n+1,10^(n+1)-1,2,f=factor(i);
               ms=matsize(f);if((ms[1]==1&&f[1,2]==2)||(ms[1]==2&&f[1,2]==1&&f[2,
               2]==1),print1(i,",");break))) - Herman Jamke (hermanjamke(AT)fastmail.fm), 
               Oct 21 2006
%Y A098146 Cf. A046315 odd semiprimes, A098147(n)=a(n)-10^n continuation of this 
               sequence, A003717 smallest n-digit prime.
%Y A098146 Sequence in context: A029712 A136353 A136354 this_sequence A124274 A075134 
               A158789
%Y A098146 Adjacent sequences: A098143 A098144 A098145 this_sequence A098147 A098148 
               A098149
%K A098146 nonn
%O A098146 0,1
%A A098146 Hugo Pfoertner (hugo(AT)pfoertner.org), Aug 28 2004

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