s$="9876789"
n%=4
for i%=1 to 7
    locate i%,n%
    print mid$(s$,n%,5-n%)
    if i%<4 then n%=n%-1 else n%=n%+1
next

错的

不好意思,没测试
下面代码测试过:

CLS
N% = 9
IF N% > 19 OR N% < 1 THEN END
N% = INT(N% / 2) * 2 + 1
M% = INT(N% / 2)

FOR i% = 1 TO N%
      IF i% <= M% THEN
            y% = M% - i% + 2
            t% = i% * 2 - 1
        ELSE
            y% = i% - M%
            t% = (N% - i% + 1) * 2 - 1
      END IF
      K% = 9

      LOCATE i%, y%
      FOR j% = 1 TO t%
             PRINT LTRIM$(STR$(K%));
             IF j% <= INT(t% / 2) THEN K% = K% - 1 ELSE K% = K% + 1
      NEXT
NEXT