If the sum of the reciprocals of four consecutive natural numbers is equal to (77/60), then what is the sum of the two-by-two products of this natural number.
四个连续的自然数的倒数之和等于(77/60)，则这个自然数两两乘积的和等于多少．
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">2 * 5</gadget>
<output>10</output>

<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">6 + 8 + 10 + 12 + 15 + 20</gadget>
<output>71</output>

<result>71</result>