|
Search: id:A117483
|
|
|
| A117483 |
|
Numbers n for which pi(phi(n))equals phi(pi(n)). |
|
+0
1
|
|
| 0, 1, 3, 4, 5, 8, 10, 11, 17, 20, 22, 30, 31, 41, 50, 59, 67, 75, 83, 109, 127, 157, 174, 179, 191, 200, 211, 241, 277, 283, 331, 353, 360, 367, 401, 414, 431, 460, 461, 475, 509, 547, 563, 587, 599, 617, 709, 739, 773, 797, 859, 877, 919, 942, 960, 967, 991, 1014
(list; graph; listen)
|
|
|
OFFSET
|
1,3
|
|
|
FORMULA
|
a(n)=pi(phi(n))= phi(pi(n))
|
|
EXAMPLE
|
a(75)= 12 because pi(phi(75))= pi(40)= 12 and phi(pi(75))= phi(21)=12
a(75)= 12 because pi(phi(75))= pi(40)= 12 and phi(pi(75))= phi(21)=12
Also 0 is a term since pi(phi(0))=pi(0)=0 and phi(pi(0))=phi(0)=0; 1 is a term since pi(phi(1))=pi(1)=0 and phi(pi(1))=phi(0)=0.
|
|
MAPLE
|
with(numtheory): a:=proc(n) if pi(phi(n))=phi(pi(n)) then n else fi end: seq(a(n), n=0..1350); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 30 2006
|
|
MATHEMATICA
|
Select[Range[0, 1030], PrimePi@ EulerPhi@# == EulerPhi@ PrimePi@# &] (* Robert G. Wilson v *)
|
|
CROSSREFS
|
Sequence in context: A001602 A087012 A047366 this_sequence A028288 A118250 A079136
Adjacent sequences: A117480 A117481 A117482 this_sequence A117484 A117485 A117486
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Luc Stevens (lms022(AT)yahoo.com), Apr 25 2006
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(at)rgwv.com) and Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 27 2006
|
|
|
Search completed in 0.002 seconds
|
