<PRE><B>Question 536292</B>
Usually the pattern becomes clear after you examine the first 3-5 terms.&lt;P&gt;
Each friend kisses every other friend twice.&lt;P&gt;
f=2, k=4  -----&gt;4=2*2*1&lt;P&gt;
f=3, k=12 -----&gt;12=3*2*2&lt;P&gt;
f=4, k=24-----&gt;24=4*2*3&lt;P&gt;
Note that each time the first term is f, the second term is 2, and the third term is one less than f&lt;P&gt;

k=f*2*(f-1)
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