AE expression: Layer info Numbers

Layer_Info_Numbers.jsx

// Sometimes you need to burn in your layer(s) information into your renders
// 1. Create an empty text layer
// 2. Unfold its properties to Text -> Source Text
// 3. Click its stopwatch while pressing Alt
// 4. Paste this expression. You can exclude these descriptive lines starting with //
// 5. Done. Now adjust the text properties to your preference
// This expression creates text with your composition name and current layer(s) numbers.
// If you do not want it to be included in the actual render, use Layer -> Guide Layer option
// This expression takes in account all the layers below itself, so to include all of comp layers make this text layer the topmost.
// The expression can be slow if you have some huge amount of layers in your comp.    

var p = "", st = thisLayer.index + 1;
for (var i = st; i <= thisComp.numLayers; i++) {
   if ((time > thisComp.layer(i).inPoint) && (time < thisComp.layer(i).outPoint)) {p = ((p==="") ? p + i : p + ", " + i)}
}
"comp: " + thisComp.name + "\nlayers: " + p