I sent a big bunch of flowers to the nurse as an ________ of thanks for her taking good care of my grandpa in the nursing home. ( )
(Ⅰ)求数列 {an} 的通项公式;
(Ⅱ)若数列 {bn}满足bn=(12)an+10 ,求数列 {nbn} 的前n项和Sn.