login
This site is supported by donations to The OEIS 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!)
A064539 Numbers n such that 2^n + n^2 is prime. 6
1, 3, 9, 15, 21, 33, 2007, 2127, 3759, 29355, 34653, 57285, 99069 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Last three values 2^2007+2007^2, 2^2127+2127^2, 2^3759+3759^2 were proved prime with Primo.

n is always an odd multiple of 3 (except for the first term), i.e. a(n) is a subsequence of A016945. - Lekraj Beedassy, Jan 01 2007

REFERENCES

J.-M. De Koninck & A. Mercier, 1001 Problemes en Theorie Classique Des Nombres, Problem 165 pp. 30, 160, Ellipses Paris 2004.

LINKS

Table of n, a(n) for n=1..13.

Discussion group for the primality-testing program PrimeForm.

Henri Lifchitz, Renaud Lifchitz, PRP Top Records. 2^n+n^2.

PROG

(PARI) for(n=1, 5000, if(isprime(2^n+n^2), print(n)))

CROSSREFS

Cf. A001580, A061119, A072180, A094133.

Sequence in context: A114271 A137164 A108701 * A029482 A174786 A216974

Adjacent sequences:  A064536 A064537 A064538 * A064540 A064541 A064542

KEYWORD

hard,nonn

AUTHOR

Jason Earls, Oct 16 2001

EXTENSIONS

More terms from Hugo Pfoertner, Jun 26 2004

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 20 06:37 EST 2019. Contains 319325 sequences. (Running on oeis4.)