This site is supported by donations to The OEIS Foundation.



Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A319696 Number of distinct values obtained when Euler phi (A000010) is applied to the divisors of n. 6


%S 1,1,2,2,2,2,2,3,3,2,2,3,2,2,4,4,2,3,2,4,4,2,2,4,3,2,4,4,2,4,2,5,4,2,

%T 4,5,2,2,4,5,2,4,2,4,6,2,2,5,3,3,4,4,2,4,4,6,4,2,2,5,2,2,5,6,4,4,2,4,

%U 4,4,2,7,2,2,6,4,4,4,2,6,5,2,2,6,4,2,4,6,2,6,4,4,4,2,4,6,2,3,6,6,2,4,2,6,8

%N Number of distinct values obtained when Euler phi (A000010) is applied to the divisors of n.

%H Antti Karttunen, <a href="/A319696/b319696.txt">Table of n, a(n) for n = 1..65537</a>

%F a(n) = A319695(n) + [n (mod 4) != 2], where [ ] is the Iverson bracket, resulting 0 when n = 2 mod 4, and 1 otherwise.

%e For n = 6, it has four divisors: 1, 2, 3 and 6, and applying A000010 to these gives 1, 1, 2, 2, with just two distinct values, thus a(6) = 2.

%o (PARI) A319696(n) = { my(m=Map(),s,k=0); fordiv(n,d,if(!mapisdefined(m,s=eulerphi(d)), mapput(m,s,s); k++)); (k); };

%Y Cf. A000010, A319695.

%Y Cf. also A184395, A319686.

%K nonn

%O 1,3

%A _Antti Karttunen_, Oct 02 2018

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 6 16:24 EST 2019. Contains 329808 sequences. (Running on oeis4.)