An array of pin numbers for the inputs and another one for the outputs would be a sensible approach:
#include <Servo.h>
Servo arm[3] ; // create servo object to control a servo
int arm_pins [] = { A0, A1, A2 } ; // analog pins used to connect the potentiometers
int servo_pins [] = { 9, 10, 11 } ;
void setup()
{
for (int i = 0 ; i < 3 ; i++)
arm[i].attach(servo_pins [i]); // attaches the servos to their pins
}
void loop()
{
for (int i = 0 ; i < 3 ; i++)
arm[i].write (map (analogRead (arm_pins [i]), 0, 1023, 0, 179)) ;
delay(15); // waits for the servos to get there
}
(untested, but you get the idea)