t =

0

1

2

3

4

r = 1

s = 0

1

2

4

7

12

r = 1

s = 1

2

5

11

21

38

r = 1

s = 2

4

11

26

52

98

r = 1

s = 3

7

21

52

109

212

r = 1

s = 4

12

38

98

212

424