a_n = sin(npi/2) Write the first five terms of the sequence.

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}.