Sequence created in anon PL/SQL missing initial value

Question

If I create a sequence in an anonymous PL/SQL block, with execute immediate, then perform a select nextval from that sequence outside the block, it misses it's initial value.
Easily reproducable here:
create table tab_a ( col_a number(4) not null );
begin
  execute immediate 'create sequence seq_a start with 47 increment by 1';
end;
insert into tab_a select seq_a.nextval from dual;
select * from tab_a;
This is a much simplified representation of the circumstance I found myself in, but it reproduces the effect I see.
If I drop the sequence and truncate the table, and run the statements (excluding the first) again, it works as expected. If I drop the table and run all the statements again, it returns the wrong answer again.
I don't need a workaround, the issue has been addressed long ago, but I would like to know WHY this happens. starting the sequence at 47 can be any number, it's there just to show the issue when 48 is inserted into the table. The insert could be into any table, and the from could be over any table rather than dual.
Oracle EE 11.2.0.1.0 on OE Linux, RAC and Single node.
TIA.

Answer 1

Can you show the output you get like this? Mine is a 10g DB. But sure it would work in 11g DB as well.
SQL> select * from v$version where rownum = 1;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi
SQL> drop table t;
Table dropped.
SQL> create table t (no integer not null);
Table created.
SQL> begin
  2     execute immediate 'create sequence seq start with 47 increment by 1';
  3  end;
  4  /
PL/SQL procedure successfully completed.
SQL> insert into t select seq.nextval from dual;
1 row created.
SQL> select * from t;
        NO
        47
SQL>