loop through layers setting lock and visibility

  I need to loop through the layers in the active document and set some of the layer properties to either false or true.  I was trying to a create a loop using a "for" method, but it didn't seem to work. I gave up on the "for" method because I kept running into a problem.  I don't need to set all layers with these settings just the odd ones (2,4,6, etc). Here is sample if it was written out. 

var myLayer = myDoc.layers[2];

myLayer.visible = false;

myLayer.locked = true;

var myLayer = myDoc.layers[4];

myLayer.visible = false;

myLayer.locked = true;

var myLayer = myDoc.layers[6];

myLayer.visible = false;

myLayer.locked = true;

var myLayer = myDoc.layers[8];

myLayer.visible = false;

myLayer.locked = true;

I have 208 layers, so doing it this way would be way to long. Any help would be appreciated.

Running Illustrator CC 2014.