Answer :

Given:

[tex]c_n=n(n+1)[/tex]

Required:

To find the first four terms of the sequence.

Explanation:

The first term is,

When n=1,

[tex]\begin{gathered} c_1=1(1+1) \\ =1\times2 \\ =2 \end{gathered}[/tex]

When n=2,

[tex]\begin{gathered} c_2=2(2+1) \\ =2\times3 \\ =6 \end{gathered}[/tex]

When n=3,

[tex]\begin{gathered} c_3=3(3+1) \\ =3\times4 \\ =12 \end{gathered}[/tex][tex]undefined[/tex]