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 A068885 Numerator of Sum_{k=1..n} k/phi(k). 2
 1, 3, 9, 13, 31, 43, 143, 167, 185, 215, 1141, 1321, 231, 763, 3277, 3517, 7289, 8009, 24787, 26587, 27847, 29431, 332021, 355781, 365681, 382841, 394721, 413201, 2949827, 3157727, 643003, 665179, 3417371, 3535181, 3616031, 3782351, 1279777, 3956371, 4046461 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES József Sándor, Dragoslav S. Mitrinovic, and Borislav Crstici, Handbook of Number Theory I, Springer Science & Business Media, 2005, Section I.27, page 29. LINKS Amiram Eldar, Table of n, a(n) for n = 1..1000 R. Sitaramachandrarao, On an error term of Landau - II, The Rocky Mountain Journal of Mathematics, Vol. 15, No. 2 (1985), pp. 579-588. FORMULA a(n)/A069947(n) ~ c * n - log(n)/2 + O(log(n)^(2/3)), where c = zeta(2)*zeta(3)/zeta(6) (A082695) (Sitaramachandrarao, 1985). - Amiram Eldar, Sep 18 2022 EXAMPLE 1, 3, 9/2, 13/2, 31/4, 43/4, 143/12, 167/12, 185/12, ... MATHEMATICA Numerator @ Accumulate @ Table[k/EulerPhi[k], {k, 1, 40}] (* Amiram Eldar, Sep 18 2022 *) PROG (PARI) a(n) = numerator(sum(k=1, n, k/eulerphi(k))); \\ Michel Marcus, Sep 18 2022 CROSSREFS Cf. A069947 (denominators), A000010, A028415, A048049, A082695. Sequence in context: A305913 A215443 A304664 * A305644 A316920 A018292 Adjacent sequences: A068882 A068883 A068884 * A068886 A068887 A068888 KEYWORD nonn,frac AUTHOR N. J. A. Sloane, Jun 28 2002 STATUS approved

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Last modified September 18 14:47 EDT 2024. Contains 376000 sequences. (Running on oeis4.)