21.(12分)设数列{an}满足a1=2,an+1-an=3×22n-1,
(1)求数列{an}的通项公式;
(2)令bn=nan,求数列{bn}的前n项和Sn.
22.(12分)已知数列{an}满足a1=1,|an+1-an|=pn,n∈N*.
(1)若{an}是递增数列,且a1,2a2,3a3成等差数列,求p的值;
(2)若p=,且{a2n-1}是递增数列,{a2n}是递减数列,求数列{an}的通项公式.