Question 60451
Look at the numbers in terms of what powers they are of what numbers
{{{2^2 = 4}}}
{{{2^3 = 8}}}
{{{2^4 = 16}}} etc.
and
{{{3^2 = 9}}}
{{{3^3 = 27}}}
{{{3^4 = 81}}} etc.
look at your sequence number by number
1,8,27,64,125
{{{1 = 1^2}}}
{{{8 = 2^3}}}
{{{27 = 3^3}}}
{{{64 = 4^3}}}
{{{125 = 5^3}}}
The first one is out of place but {{{1^2 = 1}}} and {{{1^3 = 1}}} also
so, the sequence is {{{n^3}}} where n is the position in the sequence.
Test yourself. What is the 11th term?
{{{1331 = 11^3}}} 
what is the 10,000th term?
{{{10^12 = 10000^3}}}
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 a, a+d, a+2d, a+3d, a+4d,...
a is the same in each term so, it's a + something
The multiplier for d looks like its position in the series minus one
n = position
{{{a + (n-1)d}}} answer
test this to see if it works for each term
1st term: {{{a + (1-1)d = a}}}
2nd term: {{{a + (2-1)d = a + d}}} etc.