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 A002732 Numbers k such that (4*k^2 + 1)/5 is prime. (Formerly M3281 N1324) 2
 4, 6, 11, 14, 21, 24, 26, 29, 31, 39, 44, 46, 51, 54, 76, 79, 89, 94, 99, 101, 111, 119, 124, 129, 131, 136, 146, 149, 154, 156, 164, 176, 179, 181, 194, 201, 211, 214, 229, 231, 239, 244, 246, 254, 261, 279, 286, 294, 301, 311, 314, 319, 326, 331, 346, 349 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES L. Euler, De numeris primis valde magnis (E283), reprinted in: Opera Omnia. Teubner, Leipzig, 1911, Series (1), Vol. 3, p. 24. N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). 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 L. Euler, De numeris primis valde magnis (E283), The Euler Archive. MATHEMATICA Select[Range[0, 400], PrimeQ[(4 #^2 + 1)/5] &] (* Vincenzo Librandi, Sep 25 2012 *) PROG (Magma) [n: n in [4..410] | IsPrime((4*n^2+1) div 5)]; // Vincenzo Librandi, Sep 25 2012 (PARI) is(n)=isprime((4*n^2+1)/5) \\ Charles R Greathouse IV, May 22 2017 CROSSREFS Sequence in context: A096833 A153357 A310591 * A144065 A343098 A036831 Adjacent sequences: A002729 A002730 A002731 * A002733 A002734 A002735 KEYWORD nonn,easy AUTHOR N. J. A. Sloane STATUS approved

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Last modified September 18 19:41 EDT 2024. Contains 376002 sequences. (Running on oeis4.)