I tried 1 and it gave me odd numbers again. A1 does the same thing.
Then perhaps the problem is an electrical one with the signal going to the analog input pin. What is it's output impedenace? Is there a common ground wired from the arduino to the circuit supplying the measurement signal?
One way to test your software is to remove your signal wire from the analog pin and first wire a ground to the analog input pin and see if your raw count value is a stable 0 value, then remove the ground wire and wire from the shield 5V pin to the analog input pin and see if your raw count value is a stable 1023 value.