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A200816 Numbers k such that (2^k - k)*2^k + 1 is prime. 7
1, 3, 4, 10, 11, 16, 47, 57, 69, 166, 327, 460, 1108, 4740, 20760, 21143 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The generalization of this sequence is possible with the primes of the form  (b^n +- k)*b^n +- 1.

LINKS

Table of n, a(n) for n=1..16.

Henri Lifchitz, New forms of primes

EXAMPLE

4 is in the sequence because (2^4 - 4)*2^4 + 1 = 193 is prime.

MATHEMATICA

lst={}; Do[If[PrimeQ[(2^n - n)*2^n+1], AppendTo[lst, n]], {n, 10^3}]; lst

PROG

(PARI) is(n)=ispseudoprime((2^n-n)<<n+1) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A200817, A200818, A200819, A200821, A200822, A200823, A200832.

Sequence in context: A225571 A191134 A196101 * A327300 A047341 A091910

Adjacent sequences:  A200813 A200814 A200815 * A200817 A200818 A200819

KEYWORD

nonn

AUTHOR

Michel Lagneau, Nov 23 2011

STATUS

approved

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Last modified January 25 23:56 EST 2022. Contains 350572 sequences. (Running on oeis4.)