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%I #10 Nov 27 2015 12:50:07
%S 1,1,3,5,27,1,3,19,15,5,33,55,123,15,115,39,127,1,23,149,27,11,393,81,
%T 255,125,27,129,15,115,227,195,125,89,247,71,143,1031,55,89,85,365,3,
%U 49,283,135,497,59,647,309,375,399,667,111,173,355,195,219,43,49
%N Least odd number k such that 3*k*2^n-1 and 3*k*2^n+1 are twin primes.
%C 54% of a(n) for n=1 to 1755 are < 0.1*n^2.
%H Pierre CAMI, <a href="/A182030/b182030.txt">Table of n, a(n) for n = 1..1755</a>
%t lon[n_]:=Module[{k=1,n2=3*2^n},While[!PrimeQ[k*n2-1]||!PrimeQ[k*n2+1], k= k+2];k]; Array[lon,60] (* _Harvey P. Dale_, Nov 27 2015 *)
%Y Cf. A210651.
%K nonn
%O 1,3
%A _Pierre CAMI_, Apr 07 2012
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