login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A138581 Numbers n such that 2^(2*n-15)-15 is prime. 0
8, 9, 10, 11, 19, 55, 125 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

2^(2*11-15)-15=113, 2^(2*19-15)-15=8388593, 2^(2*55-15)-15=39614081257132168796771975153, ...

MATHEMATICA

q=15; For[i=q, i<=q, a={}; Do[x=2^(2*n-i)-i; If[PrimeQ[x], AppendTo[a, n]], {n, 10^2}]; Print["2^(2*n-", i, ")-", i, " ", a]; i=i+2]

PROG

(PARI) is(n)=isprime(2^(2*n-15)-15) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A297134 A247455 A280290 * A323062 A097363 A152870

Adjacent sequences:  A138578 A138579 A138580 * A138582 A138583 A138584

KEYWORD

nonn,easy

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 13 2008

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 19 09:35 EST 2020. Contains 331048 sequences. (Running on oeis4.)