1.
[tex]a_{n} = 2^{n}-n+1\\\\a_{6} = 2^{6}-6+1\\\\a_{6} = 64-5\\\\\boxed{a_{6} = 59}[/tex]
2.
[tex]a_1 = 1\\a_2 = 5\\r = a_2-a_1 = 5-1 = 4\\a_{n} = 401\\n = ?\\\\a_{n} = a_1 + (n-1)\cdot r\\\\401 = 1 + (n-1)\cdot4\\\\401 = 1 + 4n - 4\\\\401 = 4n - 3\\\\4n = 401 + 3\\\\4n = 404 \ \ /:4\\\\\boxed{n = 101}\\\\\underline{Odp. \ C.}[/tex]
