OFFSET
1,3
COMMENTS
Also a(n) = Euler Phi of largest prime factor of n (previous name).
a(m*n) = max(a(m), a(n)). - Robert Israel, May 19 2015
EXAMPLE
102 = 2*3*17, so a(102) = 17 - 1 = 16.
MAPLE
with(numtheory): A070777 := n -> `if`(n=1, 1, phi(max(op(factorset(n))))): # Peter Luschny, Oct 23 2010
MATHEMATICA
a[n_] := EulerPhi[Last[FactorInteger[n]][[1]]]; Table[a[n], {n, 1, 200}] (* José María Grau Ribas, Feb 21 2010 *)
PROG
(PARI) a(n) = if (n==1, 1, vecmax(factor(n)[, 1]) - 1); \\ after A006530; Michel Marcus, May 19 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Labos Elemer, May 07 2002
EXTENSIONS
New name from Michel Marcus, May 19 2015
STATUS
approved