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Search: id:A002504
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| A002504 |
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Values of x in A002407, i.e. numbers such that 1+3x(x-1) is (a "cuban") prime.
(Formerly M0522 N0188)
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+0
3
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| 2, 3, 4, 5, 7, 10, 11, 12, 14, 15, 18, 24, 25, 26, 28, 29, 31, 33, 35, 38, 39, 42, 43, 46, 49, 50, 53, 56, 59, 63, 64, 67, 68, 75, 81, 82, 87, 89, 91, 92, 94, 96, 106, 109, 120, 124, 126, 129, 130, 137, 141, 143, 148, 154, 157, 158, 159, 165, 166, 171, 172, 173, 176, 180
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
A. J. C. Cunningham, On quasi-Mersennian numbers, Mess. Math., 41 (1912), 119-146.
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EXAMPLE
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a(1) = 2 since A002407(1)=7=1+3k(k-1) with k=2 is the smallest prime of that form.
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PROGRAM
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(PARI) for(k=1, 999, isprime(3*k*(k-1)+1)&print1(k", ")) \\ - M. F. Hasler, Nov 28 2007
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CROSSREFS
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Cf. A133431.
Adjacent sequences: A002501 A002502 A002503 this_sequence A002505 A002506 A002507
Sequence in context: A094617 A047502 A117092 this_sequence A133431 A123091 A160512
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Edited, updated (1 is no longer regarded as a prime) and extended by M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 28 2007
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