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A215439 Numbers k such that 2^k + k^2 - 1 is prime. 4
1, 2, 4, 10, 70, 134, 146, 190, 218, 292, 478, 7136, 15964, 19988, 100790, 111442, 181874, 202112 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(17) > 150000. - Giovanni Resta, Mar 19 2014
a(19) > 3*10^5. - Robert Price, Apr 30 2014
LINKS
MATHEMATICA
Select[Range[0, 9000], PrimeQ[2^# + #^2 - 1] &]
PROG
(Magma) [n: n in [0..1000] | IsPrime(2^n+n^2-1)]
(PARI) is(n)=ispseudoprime(2^n+n^2-1) \\ Charles R Greathouse IV, May 22 2017
CROSSREFS
Cf. A215434.
Sequence in context: A080090 A125263 A326949 * A120402 A182238 A110073
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Sep 03 2012
EXTENSIONS
a(13)-a(16) from Giovanni Resta, Mar 19 2014
a(17)-a(18) from Robert Price, Apr 30 2014
STATUS
approved

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Last modified February 24 16:16 EST 2024. Contains 370307 sequences. (Running on oeis4.)