Search: id:A118479
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%I A118479
%S A118479 3,11,179,1019,10091,100361,1000211,10001399,100001651,1000002359,
%T A118479 10000003001,100000026569,1000000000061,10000000019759,100000000018109,
%U A118479 1000000000029911,10000000000013741,100000000000004381
%N A118479 Least n-digit prime which is also a twin prime and Sophie Germain prime.
%e A118479 3 and 5 twin primes and 2*3+1=7 prime, so 3 is first of twin primes and 
               Sophie Germain prime, least prime like this of one digit, so a(1)=3
%e A118479 11 and 13 twin primes ans 2*11+1=23 prime, so 11 first of twin primes 
               and Sophie Germain prime, least prime like this with two digits, 
               so a(2)=11
%t A118479 f[n_] := Block[{k = 10^(n - 1)}, While[ !PrimeQ[k] || !PrimeQ[k + 2] 
               || !PrimeQ[2k + 1], k++ ]; k]; Array[f, 18] (* Robert G. Wilson v 
               *)
%Y A118479 Sequence in context: A006485 A003115 A053888 this_sequence A103836 A081484 
               A125738
%Y A118479 Adjacent sequences: A118476 A118477 A118478 this_sequence A118480 A118481 
               A118482
%K A118479 nonn
%O A118479 1,1
%A A118479 Pierre CAMI (pierrecami(AT)tele2.fr), May 05 2006
%E A118479 Edited by Robert G. Wilson v (rgwv(at)rgwv.com), May 13 2006

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