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A057185
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Numbers n such that (19^n + 1)/20 is a prime.
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15
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17, 37, 157, 163, 631, 7351, 26183, 30713, 41201, 77951, 476929
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..11.
P. Bourdelais, A Generalized Repunit Conjecture
J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
H. Lifchitz, Mersenne and Fermat primes field
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MATHEMATICA
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Select[Range[0, 10000], PrimeQ[((19^# + 1) / 20)] &] (* Vincenzo Librandi, Mar 20 2015 *)
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PROG
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(PRIME95) PRP=1, 19, 476929, 1, 0, 0, "20" # Paul Bourdelais, Mar 20 2015
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CROSSREFS
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Sequence in context: A060429 A052292 A154301 * A157467 A093343 A153685
Adjacent sequences: A057182 A057183 A057184 * A057186 A057187 A057188
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Sep 15 2000
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EXTENSIONS
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26183 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(8)-a(9) give probable primes discovered by Paul Bourdelais, Mar 15 2010
a(10) gives a probable prime discovered by Paul Bourdelais, Mar 18 2010
a(11) gives a probable prime discovered by Paul Bourdelais, Mar 20 2015
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STATUS
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approved
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