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 A069947 Denominator of Sum_{k=1..n} k/phi(k). 2
 1, 1, 2, 2, 4, 4, 12, 12, 12, 12, 60, 60, 10, 30, 120, 120, 240, 240, 720, 720, 720, 720, 7920, 7920, 7920, 7920, 7920, 7920, 55440, 55440, 11088, 11088, 55440, 55440, 55440, 55440, 18480, 55440, 55440, 55440, 55440, 55440, 55440, 11088, 11088, 11088, 255024, 255024 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 REFERENCES József Sándor, Dragoslav S. Mitrinovic, and Borislav Crstici, Handbook of Number Theory I, Springer Science & Business Media, 2005, Chapter I, p. 29, section I.27. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE 1, 3, 9/2, 13/2, 31/4, 43/4, 143/12, 167/12, 185/12, ... MAPLE map(denom, ListTools:-PartialSums([seq(n/numtheory:-phi(n), n=1..100)])); # Robert Israel, May 01 2018 MATHEMATICA Accumulate[Table[n/EulerPhi[n], {n, 50}]]//Denominator (* Harvey P. Dale, May 24 2021 *) PROG (PARI) a(n) = denominator(sum(k = 1, n, k/eulerphi(k))); \\ Amiram Eldar, Apr 25 2024 CROSSREFS Cf. A068885 (numerators), A028415, A048049. Sequence in context: A300218 A138317 A103659 * A051547 A330719 A095329 Adjacent sequences: A069944 A069945 A069946 * A069948 A069949 A069950 KEYWORD nonn,frac AUTHOR N. J. A. Sloane, Jun 28 2002 STATUS approved

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Last modified May 22 09:32 EDT 2024. Contains 372745 sequences. (Running on oeis4.)