

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
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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^nn)<<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



