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A200819 Primes of the form (2^n - n)*2^n - 1. 7
7, 191, 863, 63487, 22835963083295358096920939600178131376317399039 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The corresponding n are 2, 4, 5, 8, 77, 377, 4547, ... (see A200818).

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

For n = 377, a(6) contains 227 digits;

For n = 4547, a(7) contains 2738 digits;

For n = 8248, a(8) contains 4966 digits.

LINKS

Table of n, a(n) for n=1..5.

Henri Lifchitz, New forms of primes

EXAMPLE

191 is in the sequence because, for n = 4, a(2) = (2^4 - 4)*2^4 - 1 = 191.

MATHEMATICA

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

CROSSREFS

Cf. A200816, A200817, A200818, A200821, A200822, A200823, A200832.

Sequence in context: A303292 A010332 A198258 * A232146 A264353 A024096

Adjacent sequences:  A200816 A200817 A200818 * A200820 A200821 A200822

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 28 02:02 EDT 2020. Contains 337389 sequences. (Running on oeis4.)