OFFSET
1,1
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms 1..656 from Ray Chandler)
Project Euler, Problem 302: Strong Achilles Numbers
MATHEMATICA
achillesQ[n_] := With[{ee = FactorInteger[n][[All, 2]]}, Min[ee] > 1 && GCD @@ ee == 1];
Select[Range[10^6], achillesQ[#] && achillesQ[EulerPhi[#]]&] (* Jean-François Alcover, Sep 26 2020 *)
PROG
(PARI) isA(n)=!ispower(n) && ispowerful(n)
is(n)=isA(n) && isA(eulerphi(n)) \\ Charles R Greathouse IV, Dec 19 2013
(Python)
# uses program in A052486
from itertools import count, islice
from math import gcd
from sympy import factorint, totient
def A194085_gen(): # generator of terms
return map(lambda x:x[0], filter(lambda x:all(d>1 for d in x[1]) and gcd(*x[1])==1, map(lambda x: (x, factorint(totient(x)).values()), (A052486(i) for i in count(1)))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Kausthub Gudipati, Aug 14 2011
EXTENSIONS
Extended by Ray Chandler, Aug 16 2011
STATUS
approved