Search: id:A072059
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%I A072059
%S A072059 2,7,97,577,7507,217717,5232727,75172597,1617423307,59844662377,
%T A072059 2750790860317,109455887488447,4621264673452927,218071376383127767,
%U A072059 10914293640945722527,662082573402158125717,41249727342503299116997
%N A072059 Smallest prime p such that 2*p+1 has n distinct prime factors.
%C A072059 Note that for each n=1,...,8, the product of the smallest n-1 distinct 
               prime factors of 2*a(n)+1 is p(n)#/2, where p(n)# is the primorial 
               (A002110) of the n-th prime - and the n-th distinct prime factor 
               >= p(n+1). - Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jul 06 
               2002
%e A072059 a(4)=577=A000040(106): 2*577+1 = 1155 = 11*7*5*3, 4 distinct factors.
%o A072059 (PARI) for (n=1,8, p=1; until(isprime(p) && omega(2*p+1)==n, p++); print1(p,
               ","))
%Y A072059 Cf. A001221, A023589, A072055, A072060.
%Y A072059 Sequence in context: A056161 A076740 A112290 this_sequence A102344 A087589 
               A002812
%Y A072059 Adjacent sequences: A072056 A072057 A072058 this_sequence A072060 A072061 
               A072062
%K A072059 nonn
%O A072059 1,1
%A A072059 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 11 2002
%E A072059 More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jul 06 
               2002
%E A072059 More terms from Don Reble (djr(AT)nk.ca), Apr 15 2003

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