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 A111172 #13 May 03 2015 03:37:27
%S A111172 1,2,4,3,63,5,6115,7,8,13,761401060,11
%N A111172 Position of first occurrence of n in A039819.
%C A111172 The sequence is well-defined because every integer occurs in the sequence A039819 at least once (see S. Colton, Theorem 5). a(11) is probably between 10^8 and 10^9, a(12)=11.
%C A111172 a(14) = 47. a(15) = 170. a(16) = 42. - _Donovan Johnson_, Apr 04 2011
%H A111172 S. Colton, <a href="http://www.cs.uwaterloo.ca/journals/JIS/colton/joisol.html">Refactorable Numbers - A Machine Invention</a>, J. Integer Sequences, Vol. 2, 1999, #2.
%e A111172 a(6)=5 because the first 6 occurs in A039819 at position 5.
%t A111172 c = 0; t = Table[0, {100}]; Do[d = DivisorSigma[0, n]; If[ Mod[n, d]==0, c++; If[d < 101 && t[[d]] == 0, t[[d]] = c; Print[{d, c, n}]]], {n, 10^9}]; t (* _Robert G. Wilson v_ *)
%Y A111172 Cf. A039819, A033950.
%K A111172 nonn,more
%O A111172 1,2
%A A111172 _Franz Vrabec_, Oct 21 2005
%E A111172 a(11) from _Donovan Johnson_, Apr 04 2011