Given a series of numbers 1, 2, 4, 7, 11, 16, 22, ..., what is the 50th number.
已知一列数1，2，4，7，11，16，22，…，第50个数是多少．
<gadget id="calculator">50 * 24</gadget>
<output>1_200</output>

<gadget id="calculator">1 + 1_200 + 25</gadget>
<output>1_226</output>

<result>1_226</result>