|
|
A048049
|
|
Denominator of Sum_{k=1..n} 1/phi(k).
|
|
9
|
|
|
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
|
József Sándor, Dragoslav S. Mitrinovic, and Borislav Crstici, Handbook of Number Theory I, Springer Science & Business Media, 2005, Section I.27, page 29.
|
|
LINKS
|
|
|
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
|
|
MATHEMATICA
|
Denominator[Accumulate[Table[1/EulerPhi[k], {k, 1, 50}]]] (* Amiram Eldar, Sep 18 2022 *)
|
|
PROG
|
(PARI) a(n) = denominator(sum(k=1, n, 1/eulerphi(k))); \\ Michel Marcus, Sep 18 2022
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,frac
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|