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A127999 Numbers n such that (26^n - 1)/25 is prime. 13
7, 43, 347, 12421, 12473, 26717 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

The next term after 347 is bigger than 2250. - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 05 2007

REFERENCES

H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.

LINKS

H. Lifchitz, Mersenne and Fermat primes field

MATHEMATICA

Select[Prime[Range[100]], PrimeQ[(26^#-1)/25]&]

CROSSREFS

Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035. Cf. A127995, A127996, A127997, A127998, A128000, A098438, A128002, A128003, A128004, A128005.

Sequence in context: A042213 A193705 A164775 * A121675 A204733 A195230

Adjacent sequences:  A127996 A127997 A127998 * A128000 A128001 A128002

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007

EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008

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Last modified February 17 00:09 EST 2012. Contains 205978 sequences.