Query to return list of all missing primary key ids from table T1

Question

I found this query online that returns a start and stop for a range of all missing primary key id values from table T1. However i want to rewrite this query to return a whole list of all the missing primary key ids and not a start and stop range. any help plz?
select strt, stp
from (select m.id + 1 as strt,
(select min(id) - 1 from T1 x where x.id > m.id) as stp
from T1 m left outer join T1 r on m.id = r.id - 1 where r.id is null)x where stp is not null

Answer 1

with t as
          select  1 as id from dual union all
          select  2 as id from dual union all
          select  3 as id from dual union all
          select  5 as id from dual union all
          select  8 as id from dual union all
          select 10 as id from dual union all
          select 11 as id from dual union all
          select 20 as id from dual
select  id_start + level missing_id
  from  (
         select  id id_start,
                 nullif(lead(id) over(order by id) - 1, id) id_end
           from  t
  start with id_end is not null
  connect by prior id_start = id_start
         and prior dbms_random.random is not null
         and level <= id_end - id_start
MISSING_ID
         4
         6
         7
         9
        12
        13
        14
        15
        16
        17
        18
MISSING_ID
        19
12 rows selected.Or:
with t as
          select  1 as id from dual union all
          select  2 as id from dual union all
          select  3 as id from dual union all
          select  5 as id from dual union all
          select  8 as id from dual union all
          select 10 as id from dual union all
          select 11 as id from dual union all
          select 20 as id from dual
select  id_start + level - 1 missing_id
   from  (
          select  min(id) id_start,
                  max(id) id_end
            from  t
   connect by level <= id_end - id_start
minus
select  id
   from  t
MISSING_ID
         4
         6
         7
         9
        12
        13
        14
        15
        16
        17
        18
MISSING_ID
        19
12 rows selected.SY.