

A127997


Numbers n such that (22^n  1)/21 is prime.


9




OFFSET

1,1


COMMENTS

9029 is a term found by Richard Fischer in 2004.  Alexander Adamchuk, Feb 11 2007
No other terms < 100000.  Robert Price, Feb 25 2012


LINKS

Table of n, a(n) for n=1..9.
H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927930.
H. Lifchitz, Mersenne and Fermat primes field
Index to primes in various ranges, form ((k+1)^n1)/k


MATHEMATICA

Select[Prime[Range[100]], PrimeQ[(22^#1)/21]&]


PROG

(PARI) isok(n) = isprime((22^n1)/21); \\ Michel Marcus, Mar 13 2016


CROSSREFS

Sequence in context: A102983 A038583 A082080 * A096266 A123978 A303482
Adjacent sequences: A127994 A127995 A127996 * A127998 A127999 A128000


KEYWORD

hard,more,nonn


AUTHOR

Alexander Adamchuk, Feb 11 2007


EXTENSIONS

More terms from Ryan Propper, Mar 29 2007
27823 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008


STATUS

approved



