OFFSET
1,10
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
FORMULA
a(n) = gcd(n-1, cototient(n)) = gcd(n-1, A051953(n)).
EXAMPLE
For n = 15; n-1 = 14, cototient(15) = 15-phi(15) = 7, a(15) = gcd(14,7) = 7; For most n-s, among others for primes a(n) = 1.
MAPLE
with(numtheory); A058663:=n->igcd(n-1, n-phi(n)); seq(A058663(n), n=1..100); # Wesley Ivan Hurt, Apr 01 2014
MATHEMATICA
Table[GCD[n - 1, n - EulerPhi[n]], {n, 100}] (* Wesley Ivan Hurt, Apr 01 2014 *)
PROG
(PARI) A058663(n) = gcd(n-1, n-eulerphi(n)); \\ Antti Karttunen, Sep 25 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Dec 28 2000
STATUS
approved