*     A
*    BCD
*   EFGHI
*  JKLMNOP
* QRSTUVWXY

CLEAR 
ln = 0
FOR ln1 = 1 TO 5
    ? SPACE(5 - ln1)
    FOR ln2 = 1 TO 2 * ln1 - 1
        ln = ln + 1
        ?? CHR(ln + 64)
    ENDFOR
ENDFOR