Give a Recursive Definition with Initial Condition(s) $$a _ { 1 } = 16 , a _ { 2 } = 13 , a _ { 3 } = 10 , a _ { 4 } = 7 , \ldots$$

give a recursive definition with initial condition(s).
-The sequence $$a _ { 1 } = 16 , a _ { 2 } = 13 , a _ { 3 } = 10 , a _ { 4 } = 7 , \ldots$$