More nth Term Problems

For numbers 1-10, find the nth term. Then find the value of the 20th term.

1. 8, 13, 18, 23
2. 2, 5, 8, 11
3. 9, 13, 17, 21
4. 6, 14, 22, 30
5. 17, 27, 37, 47
6. -3, 10, 35, 72
7. 12, 40, 66, 112
8. 28, 63, 110, 169
9. -5/2, 0, 13/2, 17, 63/2
10. -5/2, 3, 21/2, 20
11. Find the sum of the first 100 odd numbers.
12. Find the sum of the first 25 odd numbers.
13. Find the sum of the first 50 odd numbers.
14. How many odd numbers are there between 1 and 299?
15. How many odd numbers are there between 1 and 75?
16. How many odd numbers are there between 1 and 183?
17. 1+3+5+...+299=?
18. 1+3+5+...+75=?
19. 1+3+5+...183=?
20. 1+3+5+...+247=?