|
| |
|
|
A063986
|
|
Numbers n such that n divides Sum_{k=1..n} A051953(k) where A051953(k)=k-Phi(k). Arithmetic mean of first n cototient values is an integer.
|
|
7
|
|
|
|
1, 4, 5, 24, 25, 249, 600, 617, 12272, 13763, 21332, 25228, 783665, 15748051, 41846733, 195853251, 2488541984, 14399065016, 21119309213, 22430204140, 43787603128, 157825075944, 206651865067, 271605149320, 374049315076, 650288309748
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
The odd terms of A048290 and A063986 are the same. - Jud McCranie, Jun 26 2005
a(27) > 10^12. - Donovan Johnson, Dec 09 2011
|
|
|
LINKS
|
Table of n, a(n) for n=1..26.
|
|
|
EXAMPLE
|
n=5: (1 + 1 + 2 + 2 + 4)/5 = 2.
|
|
|
MATHEMATICA
|
s = 0; Do[s = s + n - EulerPhi[n]; If[ IntegerQ[s/n], Print[n]], {n, 1, 10^7} ]
|
|
|
CROSSREFS
|
Cf. A051953, A000010, A002088, A048920, A000217, A050226.
Sequence in context: A338422 A171885 A331261 * A039583 A042123 A041531
Adjacent sequences: A063983 A063984 A063985 * A063987 A063988 A063989
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Labos Elemer, Sep 06 2001
|
|
|
EXTENSIONS
|
More terms from Dean Hickerson, Sep 07 2001
One more term from Robert G. Wilson v, Sep 07 2001
a(16) and a(17) from Jud McCranie, Jun 22 2005
a(18)-a(21) from Donovan Johnson, May 11 2010
a(22)-a(26) from Donovan Johnson, Dec 09 2011
|
|
|
STATUS
|
approved
|
| |
|
|
