

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
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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
Some of the results were computed using the PrimeFormGW (PFGW) primalitytesting program.  Hugo Pfoertner, Nov 14 2019


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.
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

nonn,more,hard


AUTHOR

Jason Earls, Oct 16 2001


EXTENSIONS

More terms from Hugo Pfoertner, Jun 26 2004


STATUS

approved



