InChI=1S/C20H34/c1-3-5-7-9-11-13-15-17-19-20-18-16-14-12-10-8-6-4-2/h3,5,7,9,11,13,15H,1,4,6,8,10,12,14,16-20H2,2H3/b7-5+,11-9+,15-13+