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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 (list; graph; refs; listen; history; text; internal format)
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).

LINKS

Table of n, a(n) for n=1..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

Cf. A089001, A168550, A239874, A239925.

Sequence in context: A234426 A187436 A193055 * A245483 A015388 A257714

Adjacent sequences:  A240096 A240097 A240098 * A240100 A240101 A240102

KEYWORD

nonn

AUTHOR

Zak Seidov, Apr 01 2014

STATUS

approved

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Last modified June 1 18:28 EDT 2020. Contains 334762 sequences. (Running on oeis4.)