function usedBefore(value, limit) {
  var found = "No";
  if (limit >= 2) {
    for (var i = 1; i < limit; i++) {
      if ((num[i] == value)) {
         found = "Yes";
         return found;
      }
    }
  }
  return found;
}

function fillPics(picsToGenerate) {
  num = new Array();
  num[1] = randomNum(1, numberOfPics);
  for (var i = 2; i <= picsToGenerate; i++) {
    num[i] = randomNum(1, numberOfPics);
    while (usedBefore(num[i], i) == "Yes") {
      num[i] = randomNum(1, numberOfPics);
    }
  }
  document.write('<table cellspacing="3"><tr valign="middle">');
  for (i = 1; i <= picsToGenerate; i++) {
    document.write('<td><img src="img/klfmk'+num[i]+'.jpg" alt="" title="Klik hier voor een presentatie\nvan alle tekeningen en beelden"></td>');
    if (i % newLineAfter === 0) {
       document.write('</tr><tr valign="middle">');
    }
  }
  document.write('</tr></table>');
}