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!)
 A318662 Denominators of the sequence whose Dirichlet convolution with itself yields A055653, sum of phi(d) over all unitary divisors d of n. 5
 1, 1, 2, 1, 2, 2, 2, 2, 8, 2, 2, 2, 2, 2, 4, 2, 2, 8, 2, 2, 4, 2, 2, 4, 8, 2, 16, 2, 2, 4, 2, 2, 4, 2, 4, 8, 2, 2, 4, 4, 2, 4, 2, 2, 16, 2, 2, 4, 8, 8, 4, 2, 2, 16, 4, 4, 4, 2, 2, 4, 2, 2, 16, 8, 4, 4, 2, 2, 4, 4, 2, 16, 2, 2, 16, 2, 4, 4, 2, 4, 128, 2, 2, 4, 4, 2, 4, 4, 2, 16, 4, 2, 4, 2, 4, 4, 2, 8, 16, 8, 2, 4, 2, 4, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS The sequence seems to give the denominators of several other similarly constructed "Dirichlet Square Roots". LINKS Antti Karttunen, Table of n, a(n) for n = 1..16384 FORMULA a(n) = denominator of f(n), where f(1) = 1, f(n) = (1/2) * (A055653(n) - Sum_{d|n, d>1, d 1. PROG (PARI) up_to = 1+(2^16); A055653(n) = sumdiv(n, d, if(gcd(n/d, d)==1, eulerphi(d))); \\ From A055653 DirSqrt(v) = {my(n=#v, u=vector(n)); u[1]=1; for(n=2, n, u[n]=(v[n]/v[1] - sumdiv(n, d, if(d>1&&d

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 May 26 22:58 EDT 2020. Contains 334634 sequences. (Running on oeis4.)