so we have 1,8,27
this is obviously not an arythmetic sequence ( addition )
it is a geometric sequence (multiplication and exponents)
1st term=1
2nd term=8
3rd term=27
I notcie that 8=2^3 and 27=3^3 so therefor
the nth term is
n^3
so 4th term=4^3=64
5th term=5^3=125
6th term=6^3=216 etc
the nth term is n^3