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A048049 Denominator of Sum_{k=1..n} 1/phi(k). 6
1, 1, 2, 1, 4, 4, 12, 6, 3, 12, 60, 15, 60, 60, 120, 30, 240, 80, 720, 720, 720, 720, 7920, 7920, 1584, 1584, 1584, 1584, 11088, 11088, 55440, 13860, 1386, 11088, 11088, 11088, 11088, 11088, 11088, 5544, 6930, 13860, 13860, 3465, 27720, 27720, 637560, 1275120, 182160 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, Section I.27.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Totient Summatory Function

EXAMPLE

1, 2, 5/2, 3, 13/4, 15/4, 47/12, 25/6, 13/3, 55/12, 281/60, 74/15, ...

MAPLE

map(denom, ListTools:-PartialSums(map(1/numtheory:-phi, [$1..100]))); # Robert Israel, Apr 16 2019

CROSSREFS

Cf. A000010, A028415.

Sequence in context: A034409 A209478 A211178 * A212716 A057772 A145861

Adjacent sequences:  A048046 A048047 A048048 * A048050 A048051 A048052

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Jun 28 2002

STATUS

approved

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Last modified July 16 09:13 EDT 2020. Contains 335784 sequences. (Running on oeis4.)