You can observe that
[tex]a_1=1=1^2[/tex]
[tex]a_2=4=2^2[/tex]
[tex]a_3=9=3^2[/tex]
[tex]a_4=16=4^2[/tex]
So, we can extrapolate the general rule
[tex]a_n=n^2[/tex]
So, the 100th term will be
[tex]a_{100}=100^2=10000[/tex]
