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A098438
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Numbers n such that (30^n-1)/29 is prime.
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13
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OFFSET
| 1,1
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COMMENTS
| No other terms < 100,000. - Robert Price
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REFERENCES
| H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.
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LINKS
| H. Lifchitz, Mersenne and Fermat primes field
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MATHEMATICA
| Do[If[PrimeQ[(30^n - 1)/29], Print[n]], {n, 1, 10000}] (Propper)
Select[Prime[Range[100]], PrimeQ[(30^#-1)/29]&] - Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007
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PROG
| (MAGMA) for i in [1..500] do if i mod 50 eq 0 then print "counter equals", counter; end if; if IsPrime(i) then n := 0; for j in [0..i-1] do n +:= 30^j; end for; if IsPrime(n) then print n; print i; end if; end if; end for;
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CROSSREFS
| Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035.
Cf. A127995, A127996, A127997, A127998, A127999, A128000, A128002, A128003, A128004, A128005.
Searching in the OEIS for 'repunit' gives many similar sequences.
Sequence in context: A158999 A069506 A123165 * A064772 A107989 A069504
Adjacent sequences: A098435 A098436 A098437 * A098439 A098440 A098441
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KEYWORD
| nonn,more
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AUTHOR
| Tim Honeywill, Jon Ingram and Paul Boddington (tch(AT)maths.warwick.ac.uk), Oct 26 2004
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EXTENSIONS
| a(5)-a(7), corresponding to probable primes, from Ryan Propper (rpropper(AT)stanford.edu), Jun 25 2005
a(7) = 8447 was found by Richard Fischer in 2004. - Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007
Edited by N. J. A. Sloane (njas(AT)research.att.com) Jan 25 2008 at the suggestion of Herman Jamke (hermanjamke(AT)fastmail.fm)
Edited by T. D. Noe (noe(AT)sspectra.com), Oct 30 2008
a(8)-a(10) = 72871,78857,82883 by Robert Price (pamandbobprice(AT)yahoo.com), Dec 10 2011
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