login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A304339 Fixed point of f starting with n, where f(x) = x/(largest perfect power divisor of x). 2

%I

%S 1,2,3,1,5,6,7,1,1,10,11,3,13,14,15,1,17,2,19,5,21,22,23,3,1,26,1,7,

%T 29,30,31,1,33,34,35,1,37,38,39,5,41,42,43,11,5,46,47,3,1,2,51,13,53,

%U 2,55,7,57,58,59,15,61,62,7,1,65,66,67,17,69,70,71,2

%N Fixed point of f starting with n, where f(x) = x/(largest perfect power divisor of x).

%C All terms are squarefree numbers. First differs from A304328 at a(500) = 1, A304328(500) = 4.

%H Andrew Howroyd, <a href="/A304339/b304339.txt">Table of n, a(n) for n = 1..1000</a>

%e f maps 500 -> 4 -> 1 -> 1, so a(500) = 1.

%t radQ[n_]:=And[n>1,GCD@@FactorInteger[n][[All,2]]===1];

%t op[n_]:=n/Last[Select[Divisors[n],!radQ[#]&]];

%t Table[FixedPoint[op,n],{n,200}]

%o (PARI) a(n)={while(1, my(m=1); fordiv(n, d, if(ispower(d), m=max(m,d))); if(m==1, return(n)); n/=m)} \\ _Andrew Howroyd_, Aug 26 2018

%Y Cf. A000961, A001597, A001694, A005117, A007916, A052485, A052486, A059404, A091050, A160400, A203025, A294068, A303707, A304327, A304328.

%K nonn

%O 1,2

%A _Gus Wiseman_, May 11 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 March 26 22:42 EDT 2019. Contains 321565 sequences. (Running on oeis4.)