login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A181660 Numbers at which the sum of the iterated totient function (A092693) attains a minimum. 2

%I #3 Mar 30 2012 17:22:57

%S 1,2,6,12,18,30,42,54,60,66,90,126,150,210,270,294,330,420,462,630,

%T 660,840,882,1050,1260,1470,1680,1890,2310,2730,2940,3150,3234,3570,

%U 3990,4410,4620,4830,5250,5460,5670,6090,6930,7350,8190,9030,9240,9450,9660

%N Numbers at which the sum of the iterated totient function (A092693) attains a minimum.

%C That is, for each n in this sequence, A092693(n) < A092693(m) for m > n. Do all primorials appear here?

%H T. D. Noe, <a href="/A181660/b181660.txt">Table of n, a(n) for n=1..300</a>

%t kMax=2*3*5*7*11*13; t=Table[0,{kMax}]; Do[e=EulerPhi[k]; t[[k]]=e+t[[e]], {k,2,kMax}]; mn=Infinity; Reverse[Reap[Do[If[t[[ -k]]<mn, mn=t[[ -k]]; Sow[kMax-k+1]], {k,kMax}]][[2,1]]]

%Y Cf. A181659

%K nonn

%O 1,2

%A _T. D. Noe_, Nov 04 2010

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 23 14:24 EST 2024. Contains 370283 sequences. (Running on oeis4.)