arduino pulse LED

gistfile1.c

const int LED = 3;


void setup()
{
  pinMode(LED, OUTPUT);
}

void loop()
{
  
    for (int i = 0; i<=255; i++)
  {
     analogWrite(LED,i*i/256);
     delay(10);
  }
  
      for (int i = 255; i>=0; i--)
  {
     analogWrite(LED,i*i/256);
     delay(10);
  }
}