login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A071570 a(n) = 2 * Sum_{d|n} 2^mu(d). 1
4, 5, 5, 7, 5, 10, 5, 9, 7, 10, 5, 14, 5, 10, 10, 11, 5, 14, 5, 14, 10, 10, 5, 18, 7, 10, 9, 14, 5, 20, 5, 13, 10, 10, 10, 20, 5, 10, 10, 18, 5, 20, 5, 14, 14, 10, 5, 22, 7, 14, 10, 14, 5, 18, 10, 18, 10, 10, 5, 28, 5, 10, 14, 15, 10, 20, 5, 14, 10, 20, 5, 26, 5, 10, 14, 14, 10, 20, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Asymptotically: Sum_{k=1..n} a(k) = 2*C*n*log(n) + O(n*log(n)) with C = 1.1...
MATHEMATICA
a[n_] := 2 * DivisorSum[n, 2^MoebiusMu[#] &]; Array[a, 100] (* Amiram Eldar, Jun 04 2022 *)
PROG
(PARI) for(n=1, 100, print1(2*sumdiv(n, d, 2^moebius(d)), ", "))
CROSSREFS
Cf. A008683.
Sequence in context: A316150 A110883 A178131 * A336047 A082448 A190796
KEYWORD
nonn,easy
AUTHOR
Benoit Cloitre, May 31 2002
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)