OFFSET
1,8
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
Jason Earls, Smarandache iterations of the first kind on functions involving divisors and prime factors, in Smarandache Notions Journal (2004), Vol. 14.1, pp 259-264.
EXAMPLE
a(24)=3 because 24 -> 9 -> 3 -> -1.
MATHEMATICA
Array[-1 + Length@ NestWhileList[Function[n, Max@ Differences@ # - SelectFirst[Reverse@ #, PrimeQ] &@ Divisors[n]], #, # > 0 &] &, 100] (* Michael De Vlieger, Mar 28 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Sep 23 2002
STATUS
approved