Starting from a huge integer x, repeatedly replace it with (first digit) times (digit count) and report whether the sequence eventually cycles forever.
The function F(x) returns the first digit of x multiplied by the number of digits of x.
For example, if x=932, the first digit is 9 and the number of digits is 3, so F(932)=9×3=27.
Apply F to the given x, then apply F to the result, and keep repeating. If the same number keeps coming out from some point on, x is called an FA number.