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!)
A348282 a(n) = Sum_{d|n, d>1} mu(d')^2. 0
0, 1, 1, 1, 1, 3, 1, 1, 2, 3, 1, 3, 1, 2, 2, 1, 1, 5, 1, 3, 3, 3, 1, 3, 2, 3, 2, 2, 1, 6, 1, 1, 3, 3, 2, 5, 1, 3, 2, 3, 1, 6, 1, 3, 4, 2, 1, 3, 2, 4, 2, 3, 1, 5, 2, 2, 3, 3, 1, 6, 1, 3, 5, 1, 2, 7, 1, 3, 3, 5, 1, 5, 1, 3, 4, 3, 2, 6, 1, 3, 2, 3, 1, 6, 3, 2, 2, 3, 1, 10, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,6
COMMENTS
Number of squarefree derivatives of the divisors of n.
LINKS
FORMULA
a(p) = 1 for primes p, since we have mu(p')^2 = mu(1)^2 = 1.
EXAMPLE
a(6) = 3; the divisors of 6 are 1,2,3,6 and their (arithmetic) derivatives are 0,1,1,5 respectively. 1,1,5 are squarefree, so a(6) = 3.
PROG
(PARI) ad(n) = vecsum([n/f[1]*f[2]|f<-factor(n+!n)~]); \\ A003415
a(n) = sumdiv(n, d, my(x=ad(d)); if (x>0, moebius(ad(d))^2)); \\ Michel Marcus, Oct 10 2021
CROSSREFS
Cf. A003415, A008683 (mu).
Sequence in context: A016464 A245570 A243925 * A030727 A278564 A269973
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Oct 09 2021
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 February 26 17:57 EST 2024. Contains 370352 sequences. (Running on oeis4.)