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 A063971 #11 Apr 24 2017 10:00:26
%S A063971 1,6,7,8,9,455,457,458,459,461,8167302,8167314,8167315,8167316,
%T A063971 8167328,8167330,8167335,8167336,8167346,8167347,8167348,8167350,
%U A063971 8167351,8167352,8167410,8167413
%N A063971 Values of n for which A013939(n)/n is an integer.
%C A063971 For 455, 457, 458, 459, 461 the quotient is 2. The cause of "step-like" appearance of terms is that the next integer is reached slowly with the summatory function A013939. Next "island" is expected above 500000. Similar phenomenon is observable in the analogous A050226 sequence too.
%C A063971 The quotients for "3rd island" after 8160000 equal 3. (Sep 21 2001)
%C A063971 a(27) > 10^13. - _Giovanni Resta_, Apr 24 2017
%t A063971 s = 0; Do[s = s + Length[FactorInteger[n]]; If[IntegerQ[s/n], Print[n]], {n, 1, 10000000}]
%Y A063971 Cf. A013939, A050226, A001221, A064612.
%K A063971 nonn
%O A063971 1,2
%A A063971 _Labos Elemer_, Sep 05 2001
%E A063971 More terms from _Robert G. Wilson v_, Sep 19 2001