You know T3 3 x T2 x 22 3 x 4 x T2 36 so T2 3. Applying a rule or formula to its results again and again. Therefore in the sequence of natural number each term has a common difference between them as 1 which means each time the next term calls its previous term to get executed.
We double 1 to get 2 then take that result of 2 and apply double again to get 4 then take the 4 and double it to get 8 and so on See.
The recursion function or recursion equation tells us how to find a1 a2 and so on. An an-1 5. F 1 10. 2the recursion equation for an as a function of an1 the term before it Example 11.