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%I #11 Mar 31 2012 13:22:06
%S 0,1,5,7,9,12,15,17,92,130,131,154,175,189,190,236,271,290,365,372,
%T 518,558,574,635,646,748,804,829,1066,1197,1236,1559,1941,2112,2324
%N Exponents n for which P#*2^n-1 is a lower twin prime, where P is the prime associated with n in A176994.
%e 2*3*2^0-1=5, 2*3*2^0+1=7 twin prime of 5 so a(1)=0
%e 2*3*2^1-1=11, 2*3*2^1+1=13 twin prime of 11 so a(2)=1
%e 2*3*2^2-1=23 prime but not twin prime
%e 2*3*2^3-1=47 prime but not twin prime
%e 2*3*2^4-1=95 composite
%e 2*3*5*2^4-1=479 prime but not twin prime
%e 2*3*2^5-1=191, 2*3*2^5+1=193 twin prime of 191 so a(3)=5
%Y Cf. A001359, A034386, A176994.
%K nonn
%O 1,3
%A _Pierre CAMI_, Dec 09 2010