Deleting a table in PostgreSQL without deleting an associated sequence
Try this:
ALTER SEQUENCE foo_id_seq OWNED BY NONE
then you should be able to drop the table.
To retrieve the "owner" of a sequence use the following query
SELECT s.relname as sequence_name, n.nspname as sequence_schema, t.relname as related_table, a.attname as related_column FROM pg_class s, pg_depend d, pg_class t, pg_attribute a, pg_namespace n WHERE s.relkind = 'S' AND n.oid = s.relnamespace AND d.objid = s.oid AND d.refobjid = t.oid AND (d.refobjid, d.refobjsubid) = (a.attrelid, a.attnum)