10 L=17
20 FOR I=1 TO L/2+1
30 FOR J=1 TO (L+1)/2-I+1 : PRINT " "; : NEXT
40 FOR J=1 TO I*2-1 : PRINT "*"; : NEXT
50 PRINT
60 NEXT I
70 FOR I=1 TO L/2
80 FOR J=1 TO I+1: PRINT " "; : NEXT
90 FOR J=1 TO ((L+1)/2-I)*2-1 : PRINT "*"; : NEXT
100 PRINT
110 NEXT I
