This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A107656 Numbers n such that prime(n)=d(n)*phi(n)+1, where d(n) is number of positive divisors of n. 0
 1, 2, 3, 4, 652245 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS There is no further term up to 5*10^7. LINKS EXAMPLE 652245 is in the sequence because prime(652245)=d(652245)*phi(652245)+1. MATHEMATICA Do[If[Prime[n] == DivisorSigma[0, n]*EulerPhi[n] + 1, Print[n]], {n, 50000000}] CROSSREFS Cf. A104905, A107657. Sequence in context: A228311 A258107 A307256 * A024595 A144804 A118308 Adjacent sequences:  A107653 A107654 A107655 * A107657 A107658 A107659 KEYWORD more,nonn AUTHOR Farideh Firoozbakht, Jun 06 2005 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 May 19 20:41 EDT 2019. Contains 323410 sequences. (Running on oeis4.)