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A240099
Integers n such that 2n^k + 1, for k = 2..6, are prime.
1
1, 44250, 1004004, 3490575, 3517335, 5750115, 10729026, 19193559, 20251770, 25284039, 25552194, 30204801, 33733206, 39015405, 47518809, 52463445, 58370025, 69502971, 72009429, 77086380, 78510156, 83972646, 85955475, 89190969, 90499584, 92246199, 95374005
OFFSET
1,2
COMMENTS
Note that 2n^7+1 may or may not be prime.
First n>1 such that 2n^k+1, for k=2..7, are prime, is a(4) = 3490575.
First n>1 such that 2n^k+1, for k=2..8, are prime, is 83972646.
Subsequence of A239925: a(2) = 44250 = A239925(4), a(3) = 1004004 = A239925(27).
MATHEMATICA
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 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Apr 01 2014
STATUS
approved