create sequence dropme_s;
Sequence created

create table dropme_t(id number default dropme_s.nextval, val varchar2(10));
Table created

insert into dropme_t(val) select 'row#'||rownum from dual connect by level < 10;
9 rows inserted

select * from dropme_t;
        ID VAL
---------- ----------
         1 row#1
         2 row#2
         3 row#3
         4 row#4
         5 row#5
         6 row#6
         7 row#7
         8 row#8
         9 row#9
9 rows selected