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 A087237 a(n) = (Max{x : n*pi(x) = x} - Min{x : n*pi(x) = x})/n = A087236(n)/n. 5
 3, 2, 6, 6, 21, 5, 8, 86, 18, 0, 50, 17, 55, 143, 2, 269, 454, 308, 286, 335, 36, 338, 219, 113, 4, 92, 36, 72, 296, 296, 327, 23, 2, 168, 658, 770, 90, 1274, 1454, 1514, 3259, 612, 6, 2896, 367, 15, 2011, 287, 1915 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS a(n) is the difference between the largest and smallest solutions to n = x/pi(x), divided by n, where pi(x) = A000720(x). 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.] LINKS Jan Büthe, Table of n, a(n) for n = 2..50 FORMULA a(n) = A102281(n) - A038626(n). - Farideh Firoozbakht, Jan 09 2005 EXAMPLE n=22: a(22) = (10246936436-10246935644)/22 = 792/22 = 36. 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 MATHEMATICA 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 *) CROSSREFS Cf. A038623-A038627, A057809, A087235-A087240. Cf. A102281. Sequence in context: A264400 A225367 A283479 * A275630 A102004 A233208 Adjacent sequences:  A087234 A087235 A087236 * A087238 A087239 A087240 KEYWORD nonn AUTHOR Labos Elemer, Sep 04 2003 EXTENSIONS Edited by N. J. A. Sloane, Oct 28 2008 at the suggestion of R. J. Mathar 24 additional terms from Jan Büthe, Jan 16 2015 STATUS approved

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Last modified June 20 05:01 EDT 2019. Contains 324229 sequences. (Running on oeis4.)