a(n) is the greatest integer m such that (1) written in base n it is also readable as if it is in factorial base and (2) this factorial base value is smaller 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 base 3 such that its factorial base interpretation is less than the number itself. So a(3)=79.
