24. Find three different formulas or rules for the terms of a sequence a_n if the first three terms of this sequence are 2, 3, 6.
Solution: We consider the first three terms of a sequence 2,3,6.
The simplest form of this sequence is
We can even use recursive formula for this sequence, that is,
For n \geq 3
We can also formulate the nth term of this sequence by inserting factorials and doing inspection.
Therefore, we have for n=1,2,3,...