rename_layers_groups.jsx

var groups = app.activeDocument.layerSets;

var first = parseInt(groups[0].name);

for (var i = 0; i < groups.length; i++) {

	var groupName = first + i;
	groups[i].name = groupName;

	var layers = groups[i].artLayers;

	for (var j = 0; j < layers.length; j++) {
		layers[j].name = groupName + '_' + (j + 1);
	}
}