OFFSET
1,5
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
MAPLE
A051953 := proc(n)
n-numtheory[phi](n) ;
end proc:
A070556 := proc(n)
A051953(numtheory[phi](n)) ;
end proc: # R. J. Mathar, Oct 13 2011
MATHEMATICA
Table[EulerPhi[n] - EulerPhi[EulerPhi[n]], {n, 80}] (* Vincenzo Librandi, Aug 06 2015 *)
PROG
(Magma) [EulerPhi(n)-EulerPhi(EulerPhi(n)): n in [1..100]]; // Vincenzo Librandi, Aug 06 2015
CROSSREFS
KEYWORD
nonn,look
AUTHOR
N. J. A. Sloane, May 06 2002
STATUS
approved