A column of numbers is arranged regularly like this: (1/2), (2/5), (3/10), (4/17), (5/26)..., what is the 40th number?
一列数有规律地这样排列：(1/2)、(2/5)、(3/10)、(4/17)、(5/26)…，第40个数是多少．
<gadget id="calculator">40 ** 2</gadget>
<output>1_600</output>

<gadget id="calculator">1_600 + 1</gadget>
<output>1_601</output>

<gadget id="calculator">40 / 1_601</gadget>
<output>40/1_601 = around 0.024984</output>

<result>40/1_601 = around 0.024984</result>