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A002644
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Numbers n such that (n^2 + n + 1)/21 is prime.
(Formerly M5000 N1426)
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1
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16, 25, 37, 46, 58, 88, 109, 130, 142, 151, 184, 193, 205, 247, 268, 298, 310, 319, 331, 340, 382, 394, 403, 415, 424, 457, 478, 487, 541, 550, 604, 613, 688, 697, 709, 730, 739, 751, 760, 793, 844, 865, 886, 907, 970, 1012, 1045, 1054, 1066, 1117, 1138
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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REFERENCES
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A. J. C. Cunningham, Binomial Factorisations, Vols. 1-9, Hodgson, London, 1923-1929; see Vol. 1, pp. 245-259.
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).
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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MATHEMATICA
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Select[Range[1200], PrimeQ[(#^2 + # + 1)/21] &] (* Vincenzo Librandi, Sep 25 2012 *)
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CROSSREFS
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Sequence in context: A030676 A218439 A192689 * A118489 A110922 A065408
Adjacent sequences: A002641 A002642 A002643 * A002645 A002646 A002647
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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More terms from Larry Reeves (larryr(AT)acm.org), Sep 21 2000
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STATUS
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approved
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