declare
    object_exists exception;
    pragma exception_init (object_exists , -00955);
begin
    execute immediate 'CREATE SEQUENCE REGION_METROPOLITANA_SEQ 
						MINVALUE 1 MAXVALUE 9999999999999999999999999999 INCREMENT BY 1 
						START WITH 1 CACHE 20 NOORDER NOCYCLE';
    exception when object_exists then null;
end;