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Number of different pairs of primes p and q with p<q such that 6*r(n)=p+q with r(i)=i-th prime
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%I #3 Mar 31 2012 13:22:06

%S 1,2,3,4,6,7,8,10,8,11,13,11,16,14,16,15,20,18,17,21,21,23,23,22,25,

%T 27,26,25,29,28,30,30,29,33,34,34,34,35,36,40,40,39,38,42,40,45,42,45,

%U 44,47,45,50,45,51,46,47,53,55,54,56,52,55,54,53,61,55,58,59,59,62,63,64

%N Number of different pairs of primes p and q with p<q such that 6*r(n)=p+q with r(i)=i-th prime

%C The sequence is infinite

%e 6*2=12 5+7=12, 2=r(1) so a(1)=1 6*3=18 5+13=18, 7+11=18, 3=r(2) so a(2)=2 6*5=30 7+23=30, 11+19=30, 13+17=30, 5=r(3) so a(3)=3

%K nonn

%O 1,2

%A _Pierre CAMI_, Sep 11 2008