OFFSET
1,1
COMMENTS
This is the largest single divisor contributing to A136021(n).
If 4 concatenated with n-1 nines is prime, it will be the largest factor. This candidate does not work for n=6 because 499999 is not prime.
LINKS
Robert Israel, Table of n, a(n) for n = 1..501
EXAMPLE
a(3)=499 because it is the largest prime factor of all k<=10^3; the largest k in that interval with this factor is k=2*499 = 998.
MAPLE
5, seq(prevprime(5*10^n), n=1..100); # Robert Israel, Jul 21 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Enoch Haga, Dec 12 2007
EXTENSIONS
Edited and more terms added by R. J. Mathar, Apr 17 2009
STATUS
approved