a(n) is the greatest integer m such that (1) written in factorial base it is also readable as if it is in base n and (2) this base n value is greater than or equal to m.
We have 2221 in base 3 is equal to 79 and in factorial base is equal to 65. There is no greater number in factorial base such that its base 3 interpretation is greater than the number itself. So a(3)=65.
