

A373453


Iterate the function x < phi(sigma(x)). The sequence has the smallest member of cycles of length 3.


8




OFFSET

1,1


COMMENTS

69672960000 is also a term in the sequence.
a(7) <= 2704853606400. The numbers 242595672883200000, 66217181184000000000 and 185577469193591193600 are also terms.  Giorgos Kalogeropoulos, Jun 18 2024
4672651788288000 is also a term.  Jud McCranie, Jun 18 2024
The sequence is complete through 10^13.  Jud McCranie, Sep 14 2024


LINKS



EXAMPLE

16 > 30 > 24 > 16, so 16 (the smallest term) is in the sequence.


PROG

(PARI) isok(x) = my(y = eulerphi(sigma(x))); if (y > x, my(z = eulerphi(sigma(y))); if (z > x, x == eulerphi(sigma(z)))); \\ Michel Marcus, Jun 07 2024


CROSSREFS



KEYWORD

nonn,more,changed


AUTHOR



EXTENSIONS



STATUS

approved



