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Least j such that 6*p(j)*M(n)-1 is prime with p(j)=j-th prime and M(n) = Mersenne prime
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%I #3 Mar 31 2012 13:22:06

%S 2,1,2,1,4,3,12,31,2,14,19,15,17,467,37,111,1382,4830,276,1962,360,

%T 1749,2857,17253,9414,11974,30167,18822,21387,24721

%N Least j such that 6*p(j)*M(n)-1 is prime with p(j)=j-th prime and M(n) = Mersenne prime

%e 6*3*(2^2-1)-1=53 prime 2^2-1=M(1) 3=p(2) so j(1)=2 6*2*(2^3-1)-1=83 prime 2^3-1=M(2) 2=p(1) so j(2)=1

%K nonn

%O 1,1

%A _Pierre CAMI_, Feb 27 2009