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 A087237 #28 Jan 16 2018 02:40:03
%S A087237 3,2,6,6,21,5,8,86,18,0,50,17,55,143,2,269,454,308,286,335,36,338,219,
%T A087237 113,4,92,36,72,296,296,327,23,2,168,658,770,90,1274,1454,1514,3259,
%U A087237 612,6,2896,367,15,2011,287,1915
%N A087237 a(n) = (Max{x : n*pi(x) = x} - Min{x : n*pi(x) = x})/n = A087236(n)/n.
%C A087237 a(n) is the difference between the largest and smallest solutions to n = x/pi(x), divided by n, where pi(x) = A000720(x).
%C A087237 Equivalently, a(n) is the difference between largest solution and smallest natural solution of the equation pi(n*x) = x. - _Farideh Firoozbakht_, Jan 09 2005 [_Max Alekseyev_ observes that this is trivially equivalent to the first definition.]
%H A087237 Jan Büthe, <a href="/A087237/b087237.txt">Table of n, a(n) for n = 2..50</a>
%F A087237 a(n) = A102281(n) - A038626(n). - _Farideh Firoozbakht_, Jan 09 2005
%e A087237 n=22: a(22) = (10246936436-10246935644)/22 = 792/22 = 36.
%e A087237 a(2) = 3 because 1, 2, 3 & 4 are all solutions of pi(2*x) = x and 4 - 1 = 3; a(11) = 0 because 15927 is the only solution of the equation pi(11*x) = x and 15927 - 15927 = 0. - _Farideh Firoozbakht_, Jan 09 2005
%t A087237 MapIndexed[(Last@ #1 - First@ #1)/(First@ #2 + 1) &, Values@ Rest@ KeySort@ PositionIndex@ Table[n/PrimePi[n] /. k_ /; Not@ IntegerQ@ k -> 0, {n, 2, 10^6}]] (* _Michael De Vlieger_, Mar 25 2017, Version 10 *)
%Y A087237 Cf. A038623-A038627, A057809, A087235-A087240.
%Y A087237 Cf. A102281.
%K A087237 nonn
%O A087237 2,1
%A A087237 _Labos Elemer_, Sep 04 2003
%E A087237 Edited by _N. J. A. Sloane_, Oct 28 2008 at the suggestion of _R. J. Mathar_
%E A087237 24 additional terms from _Jan Büthe_, Jan 16 2015