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!)
 A318320 a(n) = (psi(n) - phi(n))/2. 6
 0, 1, 1, 2, 1, 5, 1, 4, 3, 7, 1, 10, 1, 9, 8, 8, 1, 15, 1, 14, 10, 13, 1, 20, 5, 15, 9, 18, 1, 32, 1, 16, 14, 19, 12, 30, 1, 21, 16, 28, 1, 42, 1, 26, 24, 25, 1, 40, 7, 35, 20, 30, 1, 45, 16, 36, 22, 31, 1, 64, 1, 33, 30, 32, 18, 62, 1, 38, 26, 60, 1, 60, 1, 39, 40, 42, 18, 72, 1, 56, 27, 43, 1, 84, 22, 45, 32, 52, 1, 96 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) = (A001615(n) - A000010(n))/2 = A292786(n)/2. a(n) = A291784(n) - A000010(n). a(n) = A318326(n) + A318442(n). PROG (PARI) A318320(n) = sumdiv(n, d, (-1==moebius(n/d))*d); (PARI) A318320(n) = ((n*sumdivmult(n, d, issquarefree(d)/d))-eulerphi(n))/2; CROSSREFS Cf. A000010, A001615, A291784, A292786, A318325, A318326, A318442. Differs from A069359 for the first time at n=30, where a(30) = 32, while A069359(30) = 31. Sequence in context: A249274 A205443 A069359 * A014652 A060448 A090080 Adjacent sequences:  A318317 A318318 A318319 * A318321 A318322 A318323 KEYWORD nonn,look AUTHOR Antti Karttunen, Aug 26 2018 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 August 10 07:37 EDT 2020. Contains 336368 sequences. (Running on oeis4.)