Något sånt här?
create or replace procedure next_val (p_sequence_name varchar2)
as
v_nextval integer;
v_select varchar2(100);
begin
v_select := 'select '||p_sequence_name||'.nextval from dual';
execute immediate v_select into v_nextval;
dbms_output.put_line('Nextval is: '||TO_CHAR(v_nextval));
end;