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A007591 Numbers n such that n^2+4 is prime.
(Formerly M2416)
19
1, 3, 5, 7, 13, 15, 17, 27, 33, 35, 37, 45, 47, 57, 65, 67, 73, 85, 87, 95, 97, 103, 115, 117, 125, 135, 137, 147, 155, 163, 167, 177, 183, 193, 203, 207, 215, 217, 233, 235, 243, 245, 253, 255, 265, 267, 275, 277, 287, 293, 303, 307, 313, 317, 347, 357, 373, 375 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Near-Square Prime

MATHEMATICA

lst={}; Do[If[PrimeQ[n^2+4], Print[n]; AppendTo[lst, n]], {n, 10^5}]; lst [From Vladimir Joseph Stephan Orlovsky, Aug 21 2008]

Select[Range[0, 400], PrimeQ[#^2 + 4] &] (* Vincenzo Librandi, Sep 25 2012 *)

PROG

(MAGMA) [n: n in [0..400] | IsPrime(n^2+4)]; [From Vincenzo Librandi, Nov 18 2010]

(PARI) select(n->isprime(n^4+4), vector(500, n, 2*n-1)) \\ Charles R Greathouse IV, Sep 25 2012

CROSSREFS

Sequence in context: A092793 A024909 A063241 * A097687 A032911 A157834

Adjacent sequences:  A007588 A007589 A007590 * A007592 A007593 A007594

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, R. K. Guy.

STATUS

approved

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Last modified December 22 17:45 EST 2014. Contains 252365 sequences.