S
n
in terms of x
n
S
n
in terms of x
n
1
1
-1
0
1
0
0
0
0
0
0
0
0
-2
0
1
0
0
0
0
0
0
1
0
-3
0
1
0
0
0
0
0
0
3
0
-4
0
1
0
0
0
0
-1
0
6
0
-5
0
1
0
0
0
0
-4
0
10
0
-6
0
1
0
0
1
0
-10
0
15
0
-7
0
1
0
0
5
0
-20
0
21
0
-8
0
1
Reference: Abramowitz p. 797.
