Nested FOR loops

Nested FOR loops:

SQL>DECLARE
    n NUMBER:=&no;
    v VARCHAR2(100);
    BEGIN
    FOR i IN 1..n
    LOOP
    FOR k IN 1..i
    LOOP
    v:=v||’ ‘||K;
    END LOOP;
    display(v);
    v:=null;
    END LOOP;
    END;