%I
%S 1,44250,1004004,3490575,3517335,5750115,10729026,19193559,20251770,
%T 25284039,25552194,30204801,33733206,39015405,47518809,52463445,
%U 58370025,69502971,72009429,77086380,78510156,83972646,85955475,89190969,90499584,92246199,95374005
%N Integers n such that 2n^k + 1, for k = 2..6, are prime.
%C Note that 2n^7+1 may or may not be prime.
%C First n>1 such that 2n^k+1, for k=2..7, are prime, is a(4) = 3490575.
%C First n>1 such that 2n^k+1, for k=2..8, are prime, is 83972646.
%C Subsequence of A239925: a(2) = 44250 = A239925(4), a(3) = 1004004 = A239925(27).
%t Select[Range[10^8],AllTrue[2#^Range[2,6]+1,PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Mar 18 2015 *)
%Y Cf. A089001, A168550, A239874, A239925.
%K nonn
%O 1,2
%A _Zak Seidov_, Apr 01 2014
