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Search: id:A049407
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| A049407 |
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Numbers n such that n^3+n+1 is prime. |
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33
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| 1, 2, 3, 5, 6, 8, 9, 12, 15, 17, 18, 21, 29, 30, 32, 39, 41, 42, 44, 48, 53, 54, 56, 60, 69, 71, 74, 77, 83, 87, 95, 102, 104, 108, 116, 117, 120, 126, 131, 135, 143, 144, 146, 152, 153, 155, 162, 168, 177, 179, 180, 186, 191, 207, 212, 219, 221, 225, 239, 240, 243
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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For s = 5,8,11,14,17,20,..., n_s=1+n+n^s is always composite for any n>1. Also for n=1, n_s=3 is a prime for any s. Here we consider the case s=3.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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EXAMPLE
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3 is OK because at s=3, n=3, n_s=1+n+n^s=31 is a prime.
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MATHEMATICA
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lst={}; Do[If[PrimeQ[n^3+n+1], AppendTo[lst, n]], {n, 10^3}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Sep 08 2008]
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CROSSREFS
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Cf. A002384, A075723, A049408.
Sequence in context: A127936 A096276 A075725 this_sequence A030759 A030709 A058588
Adjacent sequences: A049404 A049405 A049406 this_sequence A049408 A049409 A049410
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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