OFFSET
1,4
COMMENTS
a(15) is unknown, since there is no known Wieferich prime to base 47 (cf. Fischer link).
LINKS
EXAMPLE
The trajectory of 31 starts 31, 7, 5, 2, 1093, 2, 1093, 2, 1093, ...., entering a repeating cycle consisting of the terms 2 and 1093. There are three terms before the cycle, so a(11) = 3.
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Felix Fröhlich, Feb 05 2016
STATUS
approved