

A373454


Iterate the function x < phi(sigma(x)). The sequence has the smallest member of cycles of length 4.


8




OFFSET

1,1


COMMENTS



LINKS



EXAMPLE

576 > 1512 > 1280 > 864 > 576, so 576 (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(eulerphi(sigma(z)))))); \\ Michel Marcus, Jun 07 2024


CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



