Zigzag conformations:

The result of it is the most stable conformation for butane is in which the C-C bonds are at torsional angles of 180? which results in a 'zigzag' shape. In this conformation, the carbon atoms and C-C bonds are as far except for each other as possible. The most stable conformations for longer chain hydrocarbons will as well be zigzag. Though, since bond rotation is taking place all the time for all the C-C bonds, it is not likely that several molecules will be in a perfect zigzag shape at any one time.

Figure:   Zigzag conformations of (a) butane; (b) hexane; (c) octane; (d) decane.