1. Write a recursive function to calculate the factorial of a number.
2. Write a recursive function to find the nth Fibonacci number.
3. Write a recursive function to reverse a string.
4. Write a recursive function to count the number of digits in a number.
5. Write a recursive function to find the sum of an array of numbers.
6. Write a recursive function to check if a string is a palindrome.
7. Write a recursive function to print all natural numbers from n to 1.
8. Write a recursive function to calculate the power of a number.
9. Write a recursive function to find the greatest common divisor (GCD) of two numbers.
10. Write a recursive function to print the first n prime numbers.
11. Write a recursive function to generate all subsets of a set.
12. Write a recursive function to find the length of a string.
13. Write a recursive function to determine if a number is even or odd.
14. Write a recursive function to flatten a nested list.
15. Write a recursive function to count the number of vowels in a string.
16. Write a recursive function to find the minimum element in an array.
17. Write a recursive function to find the maximum element in an array.
18. Write a recursive function to sum the elements of a linked list.
19. Write a recursive function to check if two strings are anagrams.
20. Write a recursive function to find the binary representation of a number.
21. Write a recursive function to remove duplicates from a list.
22. Write a recursive function to generate permutations of a string.
23. Write a recursive function to calculate the sum of the digits of a number.
24. Write a recursive function to find the last occurrence of an element in an array.
25. Write a recursive function to merge two sorted arrays.
26. Write a recursive function to find the nth triangular number.
27. Write a recursive function to generate the nth row of Pascal's triangle.
28. Write a recursive function to calculate the length of a linked list.
29. Write a recursive function to reverse a linked list.
30. Write a recursive function to find the LCM of two numbers.
31. Write a recursive function to find the number of ways to climb stairs.
32. Write a recursive function to count the occurrences of a character in a string.
33. Write a recursive function to convert a decimal number to binary.
34. Write a recursive function to find all paths in a maze.
35. Write a recursive function to calculate the sum of all even numbers in a list.
36. Write a recursive function to calculate the sum of all odd numbers in a list.
37. Write a recursive function to check if a number is a perfect square.
38. Write a recursive function to check if a string contains only digits.
39. Write a recursive function to find the first occurrence of an element in an array.
40. Write a recursive function to calculate the Fibonacci sequence up to n terms.