code: public static final String getString(int index, boolean lowercase) {
  		if (index < 1) return "";
  	    index--;
  	    	
  	    int bytes = 1;
  	    int start = 0;
  	    int symbols = 24;  
  	   	while(index >= symbols + start) {
  	   		bytes++;
  	   	    start += symbols;
  	   		symbols *= 24;
  	   	}
  	   	      
  	   	int c = index - start;
  	   	char[] value = new char[bytes];
  	   	while(bytes > 0) {
  	   		bytes--;
  	   		value[bytes] = (char)(c % 24);
  	   		if (value[bytes] > 16) value[bytes]++;
  	   		value[bytes] += (lowercase ? 945 : 913);
  	   		value[bytes] = SpecialSymbol.getCorrespondingSymbol(value[bytes]);
  	   		c /= 24;
  	   	}
  	   	
  	   	return String.valueOf(value);
  	}
docs: Changes an int into a Greek letter combination.
  @param index the original number
  @return the letter combination