7.
.已知数列\(\{\)\(a_{n}\)\(\}\)满足:\(a\)\({\,\!}_{1}\)\(+\)\(3\)\(a\)\({\,\!}_{2}\)\(+\)\(5\)\(a\)\({\,\!}_{3}\)\(+\)\(…\)\(+\)\((2\)\(n-\)\(1)·\)\(a_{n}=\)\((\)\(n-\)\(1)·3\)\({\,\!}^{n+}\)\({\,\!}^{1}\)\(+\)\(3(\)\(n\)\(∈N\)\({\,\!}^{*}\)\()\),则数列\(\{\)\(a_{n}\)\(\}\)的通项公式\(a_{n}=\) .