OFFSET
1,7
LINKS
Harry J. Smith, Table of n, a(n) for n=1,...,1000
FORMULA
EXAMPLE
a(100) = 8, since phi(100) = 40, 100 - phi(100) = 60 = cototient(100), cototient(40) = 40 - 16 = 24, totient(60) = 16 so a(100) = 24 - 16 = 8.
MATHEMATICA
coTotient[n_] := n - EulerPhi@n; A065152[n_] := coTotient@ EulerPhi@ n - EulerPhi@ coTotient@ n; Array[A065152, 102] (* Robert G. Wilson v, Feb 24 2010 *)
PROG
(PARI) { for (n = 1, 1000, t=eulerphi(n); c=n - t; if (n>1, a=t - eulerphi(t) - eulerphi(c), a=0); write("b065152.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 13 2009
CROSSREFS
KEYWORD
sign
AUTHOR
Labos Elemer, Oct 19 2001
STATUS
approved