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 A007591 Numbers k such that k^2 + 4 is prime. (Formerly M2416) 28
 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 (* 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)]; // Vincenzo Librandi, Nov 18 2010 (PARI) select(n->isprime(n^2+4), vector(500, n, 2*n-1)) \\ Charles R Greathouse IV, Sep 25 2012 CROSSREFS Other sequences of the type "Numbers k such that k^2 + i is prime": A005574 (i=1), A067201 (i=2), A049422 (i=3), this sequence (i=4), A078402 (i=5), A114269 (i=6), A114270 (i=7), A114271 (i=8), A114272 (i=9), A114273 (i=10), A114274 (i=11), A114275 (i=12). Sequence in context: A285130 A024909 A063241 * A097687 A032911 A157834 Adjacent sequences:  A007588 A007589 A007590 * A007592 A007593 A007594 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified August 24 22:49 EDT 2019. Contains 326314 sequences. (Running on oeis4.)