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

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).

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