This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A136023 #8 Jul 21 2014 12:58:18 %S A136023 5,47,499,4999,49999,499979,4999999,49999991,499999993,4999999937, %T A136023 49999999967,499999999979,4999999999937,49999999999981, %U A136023 499999999999999,4999999999999997,49999999999999993,499999999999999931,4999999999999999963,49999999999999999951 %N A136023 The largest prime factor among all composites <= 10^n. %C A136023 This is the largest single divisor contributing to A136021(n). %C A136023 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 A136023 Robert Israel, <a href="/A136023/b136023.txt">Table of n, a(n) for n = 1..501</a> %e A136023 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 A136023 5, seq(prevprime(5*10^n),n=1..100); # _Robert Israel_, Jul 21 2014 %Y A136023 Cf. A136021, A052369. %K A136023 nonn %O A136023 1,1 %A A136023 _Enoch Haga_, Dec 12 2007 %E A136023 Edited and more terms added by _R. J. Mathar_, Apr 17 2009