OFFSET
1,3
COMMENTS
89 is the first number that will not reach zero under iteration of f(x) = reverse(x) - maxdigit(x) since 98-9=89. It is conjectured that 0 and 89 are the only fixed points of f.
EXAMPLE
a(4)=7 because A097155(4)=2125 and 2125 -> 5207 -> 7018 -> 8099 -> 9899 -> 9980 -> 890 -> 89 takes 7 steps to reach 89.
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Jason Earls, Aug 01 2004
STATUS
approved