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 A193992 #20 Oct 12 2013 21:52:30
%S A193992 2,5,8,17,24,54,62,91,102,132,149,264,281,316,385,503,527,762,790,
%T A193992 1035,1154,1278,1378,2304,2374,2498,2575,3122,3910,11330,11714,15400,
%U A193992 15478,15642,16039,17892,17909,17968,18401,22238,23747,38524,38728,40625,41101
%N A193992 Position where 10^n-1 occurs in the Kaprekar sequence A006886.
%C A193992 Partial sums of A194232.
%C A193992 The Mathematica code computes 50 terms, but only these 45 terms are correct.
%H A193992 Hans Havermann, <a href="/A193992/b193992.txt">Table of n, a(n) for n = 1..196</a>
%H A193992 <a href="/index/Coi#Colombian">Index entries for Colombian or self numbers and related sequences</a>
%t A193992 Inv[a_, b_] := PowerMod[a, -1, b]; t = {1}; Do[h = 10^k-1; d = Divisors[h]; d2 = Select[d, GCD[#, h/#] == 1 &]; AppendTo[t, h]; Do[AppendTo[t, d2[[i]]*Inv[d2[[i]], h/d2[[i]]]], {i, 2, Length[d2]-1}], {k, 50}]; t = Union[t]; Table[Position[t, 10^n-1, 1, 1][[1,1]], {n, Log[10, t[[-1]]]}]
%Y A193992 Cf. A006886, A194232.
%K A193992 nonn,base
%O A193992 1,1
%A A193992 _T. D. Noe_, Aug 17 2011