Question 60451
1,8,27,64,125,...  

You need to identify the relationship between the numbers.  All of these numbers are perfect cubes, so the relationship is:
{{{(matrix(7,3, Term, Formula, Value, 1, 1^3, 1, 2, 2^3, 8, 3, 3^3, 9, 4, 4^3, 64, 5, 5^3, 125, N, N^3, "_"))}}}

For the terms with variables, the relationship is already given to you:
{{{(matrix(7,2, Term, Formula, 
1, a, 2, a+d, 3, a+2d, 4, a+3d, 5, a+4d, N, a+(N-1)*d))}}}