SillyCalculator.gs

function onOpen() {
  var spreadsheet = SpreadsheetApp.getActive();
  var menuItems = [
    {name: 'Generate values', functionName: 'draknek'}
  ];
  spreadsheet.addMenu('Macro cleverness', menuItems);
}

function draknek(){
  var outputSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Generated values");
  
  outputSheet.getRange(2,2,20,20).setValue(''); // Not necessary, just here so you can see it running
  
  var i = 2; // Starts at 1 not 0!
  
  while (true) {
    var input_1 = outputSheet.getRange(i, 1).getValue();
    
    if (input_1 == '') break;
    
    var j = 2; // Starts at 1 not 0!
    
    while (true) {
      var input_2 = outputSheet.getRange(1, j).getValue();
      
      if (input_2 == '') break;
      
      var output = draknek_calculate(input_1, input_2);
      
      outputSheet.getRange(i, j).setValue(output);
      
      j++;
    }
    
    i++;
  }
  
}

function draknek_calculate(a, b){
  var calcSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Calculator");
  
  calcSheet.getRange("A1").setValue(a);
  calcSheet.getRange("B1").setValue(b);
  
  return calcSheet.getRange("C1").getValue();
}