1282: 排列计数 perm
题目描述称一个1,2,...,N1,2,...,N1,2,...,N的排列P1,P2...,PnP_1,P_2...,P_nP1,P2...,Pn是MagicMagicMagic的，当且仅当2<=i<=N2<=i<=N2<=i<=N时，Pi>Pi/2P_i>P_{i/2
