Search: id:A063638
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%I A063638
%S A063638 11,17,23,37,41,53,59,67,71,79,89,97,113,131,157,163,179,211,223,239,
%T A063638 251,269,293,307,311,331,337,367,373,379,383,397,409,419,439,449,487,
%U A063638 491,499,503,521,547,593,599,613,631,673,683,691,701,709,719,733,739
%N A063638 Primes p such that p-2 is a semiprime.
%C A063638 Primes of form p*q + 2, where p and q are primes.
%C A063638 11 is the only prime of this form where p=q. For prime p>3, 3 divides 
               p^2+2. - T. D. Noe (noe(AT)sspectra.com), Mar 01 2006
%H A063638 T. D. Noe, <a href="b063638.txt">Table of n, a(n) for n=1..1000</a>
%t A063638 Take[Select[ # + 2 & /@ Union[Flatten[Outer[Times, Prime[Range[100]], 
               Prime[Range[100]]]]], PrimeQ], 60]
%o A063638 (PARI) { n=0; for (m=2, 10^9, p=prime(m); if (bigomega(p - 2) == 2, write("b063638.txt", 
               n++, " ", p); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Aug 26 2009]
%Y A063638 Cf. A005385, A001358, A063637.
%Y A063638 Cf. A109611 (Chen primes)
%Y A063638 Sequence in context: A066938 A076812 A074207 this_sequence A141250 A096454 
               A099722
%Y A063638 Adjacent sequences: A063635 A063636 A063637 this_sequence A063639 A063640 
               A063641
%K A063638 nonn
%O A063638 1,1
%A A063638 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 21 2001

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