What is the easiest way to set a sequence to a very high value.
E.g. currval = 100, set it to point to 1100.
Instead of dropping and recreating the sequence again, use the INCREMENT BY option to reset a sequence value. You can also decrement the sequence value by incrementing it with a negative number. Don't forget to reset the increment value to 1 or as the case.
Alter sequence x increment by 1000;
select x.nextval from dual;
Alter sequence x increment by 1;
Tip taken from: