cp's OEIS Frontend

A326195 Number of iterations of x -> A009195(x) needed to reach 1 when starting from x = n, where A009195(x) = gcd(x, phi(x)).

%I A326195 #14 Dec 21 2022 16:25:00
%S A326195 0,1,1,2,1,2,1,3,2,2,1,3,1,2,1,4,1,3,1,3,2,2,1,4,2,2,3,3,1,2,1,5,1,2,
%T A326195 1,4,1,2,2,4,1,3,1,3,2,2,1,5,2,3,1,3,1,4,2,4,2,2,1,3,1,2,3,6,1,2,1,3,
%U A326195 1,2,1,5,1,2,2,3,1,3,1,5,4,2,1,4,1,2,1,4,1,3,1,3,2,2,1,6,1,3,2,4,1,2,1,4,2
%N A326195 Number of iterations of x -> A009195(x) needed to reach 1 when starting from x = n, where A009195(x) = gcd(x, phi(x)).
%H A326195 Antti Karttunen, <a href="/A326195/b326195.txt">Table of n, a(n) for n = 1..65537</a>
%F A326195 a(1) = 0; for n > 1, a(n) = 1 + a(A009195(n)).
%F A326195 a(n) < A326196(n).
%t A326195 Table[Length[NestWhileList[GCD[#,EulerPhi[#]]&,n,#>1&]]-1,{n,110}] (* _Harvey P. Dale_, Dec 21 2022 *)
%o A326195 (PARI) A326195(n) = if(1==n,0,1+A326195(gcd(n,eulerphi(n))));
%Y A326195 Cf. A000010, A009195, A326194, A326196.
%K A326195 nonn
%O A326195 1,4
%A A326195 _Antti Karttunen_, Aug 24 2019