

A296031


Numbers k such that 2^(k1)  k is prime.


0



5, 11, 15, 17, 27, 51, 57, 71, 117, 2073, 6251, 13671, 14217, 14627
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OFFSET

1,1


COMMENTS

a(15) > 200000.  Giovanni Resta, May 13 2018


LINKS

Table of n, a(n) for n=1..14.


FORMULA

a(n) = A099439(n) + 1 = A063791(n) + 2.


EXAMPLE

5 is in the sequence, because 2^4  5 = 11 is prime.


MATHEMATICA

Select[Range[6500], PrimeQ[2^(#  1)  #] &] (* Michael De Vlieger, Apr 21 2018 *)


PROG

(PARI) forstep(n=1, 10^6, 2, if(ispseudoprime(2^(n1)n), print1(n, ", "))); \\ Joerg Arndt, Apr 15 2018


CROSSREFS

Cf. A063791, A099439.
Sequence in context: A137003 A314003 A314004 * A314005 A164355 A287322
Adjacent sequences: A296028 A296029 A296030 * A296032 A296033 A296034


KEYWORD

nonn,more


AUTHOR

Thomas Gajdek, Dec 03 2017


EXTENSIONS

Edited by Joerg Arndt, Apr 15 2018


STATUS

approved



