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A240099 Integers n such that 2n^k + 1, for k = 2..6, are prime. 1

%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

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Last modified July 13 05:18 EDT 2020. Contains 335673 sequences. (Running on oeis4.)