Selecting

Hi!

Does anyone know if there is a easy way to select every 3rd or 4th or 5th fixture and so on. Like if i want to select every 5th fixture of desk channels 1 thru 50. Instead of typing 1+6+11+16+21+26... , type 1 thru 50 and then the command that selects every 5th.

/Staffan