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%I #8 Jul 21 2014 12:58:18
%S 5,47,499,4999,49999,499979,4999999,49999991,499999993,4999999937,
%T 49999999967,499999999979,4999999999937,49999999999981,
%U 499999999999999,4999999999999997,49999999999999993,499999999999999931,4999999999999999963,49999999999999999951
%N The largest prime factor among all composites <= 10^n.
%C This is the largest single divisor contributing to A136021(n).
%C 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.
%H Robert Israel, <a href="/A136023/b136023.txt">Table of n, a(n) for n = 1..501</a>
%e 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.
%p 5, seq(prevprime(5*10^n),n=1..100); # _Robert Israel_, Jul 21 2014
%Y Cf. A136021, A052369.
%K nonn
%O 1,1
%A _Enoch Haga_, Dec 12 2007
%E Edited and more terms added by _R. J. Mathar_, Apr 17 2009
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