A092767 Numbers k such that 10^k - 11 is prime.
2, 5, 8, 12, 15, 18, 20, 30, 80, 143, 152, 164, 176, 239, 291, 324, 504, 594, 983, 2894, 22226, 35371, 58437, 67863, 180979
Offset: 1
Examples
k = 5 is a term because 10^5 - 11 = 100000 - 11 = 99989, which is prime.
Links
- Makoto Kamada, Near-repdigit numbers of the form AA...AABA.
- Makoto Kamada, Prime numbers of the form 99...9989.
- Index entries for primes involving repunits.
Programs
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Mathematica
Do[ If[ PrimeQ[10^n - 11], Print[n]], {n, 3000}] (* Robert G. Wilson v, Jul 01 2005 *) -
PARI
for(n=0,5000,if(isprime(10^n-11),print1(n,","))) \\ Ryan Propper, Jun 15 2005
Extensions
4 more terms from Ryan Propper, Jun 15 2005
Edited by N. J. A. Sloane, May 04 2007
a(21)-a(22) from Robert Price, Dec 12 2010
Edited by Ray Chandler, Dec 23 2010
a(23)=58437 and a(24)=67863 from Robert Price, May 29 2011
a(25) from Kamada data by Robert Price, Apr 12 2015
Comments