`a_n=sin (npi/2)`

The subscript n represents the term number. It usually starts with n=1 which tells that `a_1` is the first term.

So to determine the first five terms, plug-in `n={1,2,3,4,5}`.

When `n=1` , the first term is:

`a_1=sin (1*pi/2)`

`a_1=1`

When `n=2` , the second term is:

`a_2=sin (2*pi/2)`

`a_2=0`

When `n=3` , the third term is:

`a_3=sin (3*pi/2)`

`a_3=-1`

When `n=4` , the fourth term is:

`a_4=sin (4*pi/2)`

`a_4=0`

And when `n=5` , the fifth term is:

`a_5=sin (5*pi/2)`

`a_5=1`

**Therefore, the first five terms of the sequence are {1, 0, -1, 0, 1}. **