见解析
分类讨论
①若A1=?时,A2=A,此时只有一种分拆.
②若A1是单元素集时,共有六种分拆,{1}与{2,3},{1}与{1,2,3},{2}与{1,3},{2}与{1,2,3},{3}与{1,2},{3}与{1,2,3}.
③若A1是双元素集时,共有12种,{1,2}与{3},{1,3},{2,3},{1,2,3};
{1,3}与{2},{1,2},{2,3},{1,2,3};
{2,3}与{1},{1,2},{1,3},{1,2,3};
④若A1=A={1,2,3},则A2={1},{2},{3},{1,2}{1,3},{2,3},{1,2,3}共7种.
综上有1+6+12+7=26.