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A127999
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Numbers n such that (26^n - 1)/25 is prime.
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9
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OFFSET
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1,1
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COMMENTS
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The next term after 347 is bigger than 2250. - Stefan Steinerberger, May 05 2007
No other terms less than 100000. - Robert Price, Mar 18 2012
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LINKS
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Table of n, a(n) for n=1..6.
H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.
H. Lifchitz, Mersenne and Fermat primes field
Index to primes in various ranges, form ((k+1)^n-1)/k
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MATHEMATICA
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Select[Prime[Range[100]], PrimeQ[(26^#-1)/25]&]
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PROG
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(PARI) is(n)=ispseudoprime((26^n-1)/25) \\ Charles R Greathouse IV, Feb 17 2017
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CROSSREFS
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Sequence in context: A042213 A193705 A164775 * A208595 A121675 A243273
Adjacent sequences: A127996 A127997 A127998 * A128000 A128001 A128002
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KEYWORD
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hard,more,nonn
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AUTHOR
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Alexander Adamchuk, Feb 11 2007
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
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STATUS
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approved
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