The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A061884 a(n) = sum_{ d | n } phi(lcm(d,n/d)), where phi(n) = Euler totient A000010. 4
 1, 2, 4, 5, 8, 8, 12, 12, 14, 16, 20, 20, 24, 24, 32, 26, 32, 28, 36, 40, 48, 40, 44, 48, 44, 48, 48, 60, 56, 64, 60, 56, 80, 64, 96, 70, 72, 72, 96, 96, 80, 96, 84, 100, 112, 88, 92, 104, 90, 88, 128, 120, 104, 96, 160, 144, 144, 112, 116, 160, 120, 120, 168, 116, 192 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS MAPLE A061884 := proc(n) local b, d: b := 0; for d from 1 to n do if irem(n, d)=0 then b := b+phi(lcm(d, n/d)); fi; od; RETURN(b); end: MATHEMATICA Table[Plus @@ Map[ EulerPhi[LCM[ #, n/# ]] &, Select[ Range@n, (Mod[n, # ] == 0) &]], {n, 65}] (* Robert G. Wilson v Sep 30 2006 *) PROG (PARI) a(n)=sumdiv(n, d, eulerphi(lcm(d, n/d))) \\ Charles R Greathouse IV, Feb 21 2013 CROSSREFS Cf. A001616, A057670, A007427. Sequence in context: A085624 A331376 A345426 * A286002 A029935 A317625 Adjacent sequences:  A061881 A061882 A061883 * A061885 A061886 A061887 KEYWORD easy,nonn AUTHOR Vladeta Jovovic, May 12 2001 STATUS approved

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

Last modified September 27 06:54 EDT 2021. Contains 347673 sequences. (Running on oeis4.)