Given the geometric sequence: 12, 54, 243, \displaystyle {12},\ {54},\ {243},\ \cdots

Find an explicit formula for an\displaystyle {a}_{{n}}, where the first term is a1=12\displaystyle {a}_{{1}}={12}.
an=\displaystyle {a}_{{n}}=  

Find a10=\displaystyle {a}_{{{10}}}=