A138602 Numbers n such that 2^(2*n-39)-39 is prime.

20, 21, 22, 23, 32, 33, 83, 140, 1122

Offset

1,1

Links

Table of n, a(n) for n=1..9.

Example

2^(2*23-39)-39=89, 2^(2*32-39)-39=33554393, 2^(2*33-39)-39=134217689, 2^(2*83-39)-39=170141183460469231731687303715884105689,

Mathematica

q=39; For[i=q, i<=q, a={}; Do[x=2^(2*n-i)-i; If[PrimeQ[x], AppendTo[a, n]], {n, 12^3}]; Print["2^(2*n-", i, ")-", i, " ", a]; i=i+2]

Prog

(PARI) is(n)=isprime(2^(2*n-39)-39) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A319678 A270045 A133895 * A346400 A347298 A326678

Adjacent sequences: A138599 A138600 A138601 * A138603 A138604 A138605

Keyword

nonn,easy

Author

Vladimir Joseph Stephan Orlovsky, May 13 2008

Status

approved