Question 1196576
<pre>

7 = {{{7*k^0}}}
x = {{{ 7*k^1}}}
y = {{{ 7*k^2}}}
189 = {{{ 7*k^3}}}  -->  {{{ k^3 = 189/7 = 27 }}} --> {{{ k = root(3,27) }}} or {{{ k=3 }}}

x = {{{7*3^1}}} = 21
y = {{{7*3^2}}} = 7*9 = 63


So the progression is  7, 21, 63, 189, ...