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A128004 Numbers n such that (38^n - 1)/37 is prime. 9
3, 7, 401, 449, 109037 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No other terms < 100000. - Robert Price, Dec 23 2011

LINKS

Table of n, a(n) for n=1..5.

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

MATHEMATICA

Select[Prime[Range[100]], PrimeQ[(38^#-1)/37]&]

PROG

(PARI) is(n)=ispseudoprime((38^n-1)/37) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Sequence in context: A248701 A103317 A104051 * A281889 A086559 A013426

Adjacent sequences:  A128001 A128002 A128003 * A128005 A128006 A128007

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 11 2007

EXTENSIONS

a(5) corresponds to a probable prime discovered by Paul Bourdelais, Oct 17 2017

STATUS

approved

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Last modified December 15 22:02 EST 2019. Contains 330012 sequences. (Running on oeis4.)