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A002640
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Numbers n such that (n^2 + n + 1)/3 is prime.
(Formerly M3301 N1331)
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1
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4, 7, 10, 13, 19, 28, 31, 34, 40, 43, 52, 70, 73, 76, 82, 85, 91, 97, 103, 112, 115, 124, 127, 136, 145, 148, 157, 166, 175, 187, 190, 199, 202, 223, 241, 244, 259, 265, 271, 274, 280, 286, 316, 325, 358, 370, 376, 385, 388, 409, 421, 427, 442, 460, 469, 472
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| 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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PROG
| (MAGMA) [ n: n in [4..500] | IsPrime((n^2+n+1) div 3) ]; [From V. Librandi, Nov 18 2010]
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CROSSREFS
| Sequence in context: A001197 A173178 A008470 * A096675 A069212 A091290
Adjacent sequences: A002637 A002638 A002639 * A002641 A002642 A002643
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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