We survey recent developments in multiplicative number theory towards
establishing the following fundamental phenomena:
the values of f(n) and f(n+1) are generally
independent unless f is of a special form. We illustrate this by
describing the proof
of a conjecture by J. Bell, N. Bruin and M. Coons classifying all automatic
multiplicative sequences.
The talk is based on a joint work with P. Kurlberg.