1, (3/4), (5/9), (7/16), a,...According to the law in this series of numbers, what should a be equal to.
1，(3/4)，(5/9)，(7/16)，a，…按这一列数中的规律，a应该等于多少．
<gadget id="calculator">7 + 2</gadget>
<output>9</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">9 / 25</gadget>
<output>9/25 = around 0.36</output>

<result>9/25 = around 0.36</result>