Question 1164946
<pre>
7, 21, 8, 72, 9, 

Start with 7

First we have 7.
7 times 3<sup>1</sup> gives 21
 Next we have 8.
8 times 3<sup>2</sup> gives 72
 Next we have 9.
9 times 3<sup>3</sup> gives 243
 Next we have 10.
10 times 3<sup>4</sup> gives 810
 Next we have 11.
11 times 3<sup>5</sup> gives 2673
 Next we have 12.
12 times 3<sup>6</sup> gives 8748
...

Edwin</pre>