DATA "0426597138","2365478109","2581470369","8103627495"
CLS
FOR seq = 1 TO 4
PRINT seq
READ s$
FOR i = 1 TO 10
dig(i) = VAL(MID$(s$, i, 1))
NEXT
FOR a = 1 TO 9
FOR b = 0 TO 9
good = 1
FOR i = 1 TO 9
v = (a * dig(i) + b) MOD 10
IF v <> dig(i + 1) THEN good = 0
NEXT
IF good THEN PRINT a, b
NEXT
NEXT
PRINT : PRINT
NEXT seq
finds that only the third column has a linear relation mod 10, and is in fact the sequence given in the example, when using the up arrow.
The others must not be of the form f(x)= (a*f(x1)+b) mod 10.

Posted by Charlie
on 20101230 11:54:10 