Search: id:A120628
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%I A120628
%S A120628 2,3,5,7,11,19,23,29,31,37,41,53,79,83,89,97,113,131,139,157,173,179,
%T A120628 191,199,211,229,233,239,251,271,281,293,307,331,337,359,367,379,419,
%U A120628 431,439,443,491,499,509,547,577,593,601,607,619,641,653,659,661,683
%N A120628 Primes such that their double is 1 away from a prime number.
%C A120628 This sequence is a variation of the sequence in the reference. However 
               this sequence should have an infinite number of terms.
%D A120628 R. Crandall and C. Pomerance, Prime Numbers A Computational Perspective, 
               Springer Verlag 2002, p. 49, exercise 1.18.
%e A120628 19 is a prime and 19*2 = 38 which is one away from 37 which is prime.
%e A120628 13 is not in the table because 13*2 = 26 is one away from 25 and 27 both 
               not
%e A120628 prime.
%o A120628 (PARI) primepm2(n,k) { local(x,p1,p2,f1,f2,r); if(k%2,r=2,r=1); for(x=1,
               n, p1=prime(x); p2=prime(x+1); if(isprime(p1*k+r)||isprime(p1*k-r), 
               print1(p1",") ) ) }
%Y A120628 Sequence in context: A069749 A081889 A078139 this_sequence A143260 A039986 
               A079346
%Y A120628 Adjacent sequences: A120625 A120626 A120627 this_sequence A120629 A120630 
               A120631
%K A120628 easy,nonn
%O A120628 1,1
%A A120628 Cino Hilliard (hillcino368(AT)gmail.com), Aug 17 2006

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