series

$$a_n=\frac{1}{n},n\epsilon\left\{1,2,3,4,5\right\}$$  

$$a_n=3n-1,n\epsilon\left\{1,2,3....\right\}$$  

$$a_n=2n^2-1$$  

$$a_n=5n,n\epsilon I^+$$  

$$5,10,15,20,25$$  

$$a_n=2n-1,n\epsilon\left\{1,2,3,...10\right\}$$  

$$a_n=4,9,16,25,..\left(n+1\right)^2...$$  

$$a_n=n^3,n\epsilon\left\{1,2,3,4,5\right\}$$  

20, 30

21, 31

20, 31

21, 31

2n+5

n+6

3n+4

$$2n^2+5$$  

3 , 7 , 11 , 15 , 19 

6 , 10 , 14 , 18 , 22

22 , 18 , 14 , 10 , 6

11 , 15 , 19 , 23 , 27

45

38

35

30

89

95

98

101

19

29

39

49

6 , –6 , 6 , –6 , …

4 , 8 , 16 , 32 , …

4 , 8 , 13 , 19 , …

–1 , 2 , –4 , 8 , …

$$3^{2-n}$$  

4n-1

$$3^{n-1}$$  

$$\frac{1}{3}\left(2^n\right)$$