Use of Serial Datatype and Sequence Issue

I am new to postgres and am in the process of creating a new database of
several 100 tables. Most of the tables have a serial datatype. When the
table is created psql says it is creating an implicit sequence. Yet
when I drop the table and even when I drop the database the sequence is
still there. When I try to re-create the table it fails beacuse the
sequence already exists. This same behaviour exists for indexes. How
can I get rid of any sequences or indexes that have been created. I
would prefer not to explicitly drop each one. Ideally I would like to
drop the table and have all related indexes, sequences dropped.

Tom