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A109713
Numbers n such that 99 * 10^n + 1 is prime.
1
1, 2, 4, 8, 16, 20, 24, 72, 200, 359, 454, 624, 1054, 2060, 6301, 8083, 8407, 13159, 65059, 74957
OFFSET
1,2
COMMENTS
All terms have been certified. No more up to 21000. Primality proof for the largest: PFGW Version 20041001.Win_Stable (v1.2 RC1b) [FFT v23.8] Primality testing 99*10^13159+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 17 Calling Brillhart-Lehmer-Selfridge with factored part 69.89% 99*10^13159+1 is prime! (29.5646s+0.0028s)
EXAMPLE
For n=8 we have 99*10^8+1 = 9900000001, which is prime.
PROG
(PARI) is(n)=ispseudoprime(99*10^n+1) \\ Charles R Greathouse IV, Jun 12 2017
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Jason Earls, Aug 08 2005
EXTENSIONS
Edited by N. J. A. Sloane at the suggestion of Herman Jamke, Jan 13 2008
a(19)-a(20) from Kamada data by Tyler Busby, Apr 16 2024
STATUS
approved