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 A189559 #18 Jan 25 2013 14:45:18 %S A189559 2,5,31,167,151,491,983,887,311,1151,1559,2111,1031,2711,4391,4271, %T A189559 3671,3191,5351,9551,11471,14759,8951,13751,11831,5591,19991,10391, %U A189559 15791,28031,30071,37511,43151,27191,40031,31391,52631,53231,35591,52391,50951 %N A189559 Least prime k such that x' = k has n solutions, where x' is the arithmetic derivative (A003415) of x. %C A189559 It is much easier finding composite numbers having many solutions. See A189558. For odd numbers, see A189560. %D A189559 See A003415. %H A189559 Donovan Johnson, <a href="/A189559/b189559.txt">Table of n, a(n) for n = 0..200</a> %F A189559 a(n) is the least prime k such that A099302(k) = n. %Y A189559 Cf. A003415, A099302, A189558, A189560. %K A189559 nonn %O A189559 0,1 %A A189559 _T. D. Noe_, Apr 24 2011