In order to solve this problem, We need to substitute the first four numbers (1,2,3,4) for n. After this we calculate:
First item:
a1= -2*1 + 4=-2+4=2
Second item:
a2= -2*2 + 4 =-4+4=0
Third item:
a3= -2*3 + 4 =-6+4=-2
Forth item:
a4= -2*4 + 4 =-8+4=-4
So the first 4 items are: 2,0,-2,-4..