drop sequence if exists test_id_seq;
create sequence test_id_seq;
drop table if exists test;
create table test(id int default nextval('test_id_seq'), name text);
alter sequence test_id_seq owned by test.id;

test=# drop table test;
DROP TABLE
test=# \d
Did not find any relations.
test=# 

drop sequence if exists test_id_seq;
create sequence test_id_seq;
drop table if exists test;
create table test(id int default nextval('test_id_seq'), name text);

test=# drop table test;
DROP TABLE
test=# \d
       List of relations
 Schema |  Name   |  Type  | Owner  
--------+-------------+----------+----------
 public | test_id_seq | sequence | postgres
(1 row)

test=#