OFFSET
1,1
COMMENTS
EXAMPLE
The cycle follows the mapping 3768 -> 4440 -> ... -> 2210-> 3768 (returning to the first element).
This cycle is entered, for example, if the mapping is started at x=246 (Cf. A098190).
MATHEMATICA
Function[s, Union@ Drop[s, #] &@ Count[DeleteDuplicates@ Map[Position[s, #] &, s], k_ /; Length@ k == 1]]@ NestList[Function[n, DivisorSum[n, # &, CoprimeQ[#, n/#] &] - EulerPhi@n], 246, 10^3] (* Michael De Vlieger, Mar 01 2017 *)
PROG
(PARI) A098189(n)=my(f=factor(n)); prod(k=1, #f~, f[k, 1]^f[k, 2]+1) - eulerphi(f)
a(n)=if(n>1, A098189(n-1), 2206) \\ Charles R Greathouse IV, Mar 01 2017
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Labos Elemer, Sep 03 2004
EXTENSIONS
Edited by R. J. Mathar, May 15 2009
STATUS
approved