void setup() {
  Serial.begin(9600);
}

void loop() {
  const float BETA = 3950;
  int valor = analogRead(A0);
  float celsius = 1 / (log(1 / (1023. / valor - 1)) / BETA
    + 1.0 / 298.15) - 273.15;
  Serial.print(valor);
  Serial.print(", ");
  Serial.print(celsius);
  Serial.println("°C");
  delay(2000);
}