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A200818 Numbers n such that (2^n - n)*2^n - 1 is prime. 7
2, 4, 5, 8, 77, 377, 4547, 8248 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No more terms < 17000. - L. Joris Perrenet, Mar 17 2020

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..8.

Henri Lifchitz, New forms of primes

EXAMPLE

4 is in the sequence because (2^4 - 4)*2^4 - 1 = 191 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. A200816, A200817, A200819, A200821, A200822, A200823, A200832.

Sequence in context: A013154 A013129 A104311 * A021980 A303496 A169624

Adjacent sequences:  A200815 A200816 A200817 * A200819 A200820 A200821

KEYWORD

nonn,hard

AUTHOR

Michel Lagneau, Nov 23 2011

EXTENSIONS

a(8) from L. Joris Perrenet, Mar 17 2020

STATUS

approved

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Last modified September 26 20:36 EDT 2020. Contains 337374 sequences. (Running on oeis4.)