Just a simple code to measure temperature with a 503 NTC Thermistor. (http://imgur.com/a/zog8f)

NTC503.ino

// include the library code:
#include <LiquidCrystal.h>
#include <math.h>

#define BUTTON_PIN A0

#define THERMISTOR_PIN A1
#define SERIES_RESISTOR 56000.0f
#define SAMPLE_SIZE 100
#define KELVIN 273.15f
#define R0 50000.0f
#define T0 298.5f // 25C
#define B 4204.0f // +- 2%


// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);

float temperature() {
  float reading, average_reading, temp;
  
  average_reading = 0;
  for (uint8_t i=0; i < SAMPLE_SIZE ; i++) {
    average_reading += float(analogRead(THERMISTOR_PIN));
  }

  average_reading = average_reading / SAMPLE_SIZE;

  reading = SERIES_RESISTOR / (1023.0f / average_reading - 1);
    
  temp = 1.0f/(1.0f/T0+(1.0f/B)*log(reading/R0)) - KELVIN;

  
  return temp;
}

void readTemp() {
  lcd.setCursor(0, 1);
  lcd.print(temperature());
}

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("Temperature C:");
}

void loop() {
  bool display_on;
  display_on = true;
  if (millis() % 2000 == 0) readTemp();
}