Question 713629
From the sequence:
 
2, 9, 21, 38, ..., 
 
the differences between terms are:
 
7, 12, 17, ... 
  
and the second level differences are:
 
5, 5, 5, ...
 
So we know that the first term of the formula is {{{(5/2)*n^2}}}.  A little experimentation shows that the actual formula is:
 
{{{(5*n^2 - n)/2}}}
 
So the sequence continues
 
2, 9, 21, 38, 60, 87, 119, ...