int POTENTIOMETER = A0;   
int LEDPIN = 13;  

int val = 0;  

void setup() 
{
  Serial.begin(9600);
  pinMode(LEDPIN, OUTPUT); 
}

void loop() 
{
  val = analogRead(POTENTIOMETER);
  Serial.println(val);
  digitalWrite(LEDPIN, HIGH);
  delay(val);
  digitalWrite(LEDPIN, LOW);
  delay(val);
}