1. Multiples of 3 or 5
  2. Even Fibonacci Numbers
  3. Largest Prime Factor
  4. Largest Palindrome Product
  5. Smallest Multiple
  6. Sum Square Difference
  7. 10001st Prime
  8. Largest Product in a Series
  9. Special Pythagorean Triplet
  10. Summation of Primes
  11. Largest Product in a Grid
  12. Highly Divisible Triangular Number
  13. Large Sum
  14. Longest Collatz Sequence
  15. Lattice Paths
  16. Power Digit Sum
  17. Number Letter Counts
  18. Maximum Path Sum I
  19. Counting Sundays
  20. Factorial Digit Sum
  21. Amicable Numbers
  22. Names Scores
  23. Non-Abundant Sums
  24. Lexicographic Permutations
  25. 1000-digit Fibonacci Number
  26. Reciprocal Cycles
  27. Quadratic Primes
  28. Number Spiral Diagonals
  29. Distinct Powers
  30. Digit Fifth Powers
  31. Coin Sums
  32. Pandigital Products
  33. Digit Cancelling Fractions
  34. Digit Factorials
  35. Circular Primes
  36. Double-base Palindromes
  37. Truncatable Primes
  38. Pandigital Multiples
  39. Integer Right Triangles
  40. Champernowne's Constant
  41. Pandigital Prime
  42. Coded Triangle Numbers
  43. Sub-string Divisibility
  44. Pentagon Numbers
  45. Triangular, Pentagonal, and Hexagonal
  46. Goldbach's Other Conjecture
  47. Distinct Primes Factors
  48. Self Powers
  49. Prime Permutations
  50. Consecutive Prime Sum
  51. Prime Digit Replacements
  52. Permuted Multiples
  53. Combinatoric Selections
  54. Poker Hands
  55. Lychrel Numbers
  56. Powerful Digit Sum
  57. Square Root Convergents
  58. Spiral Primes
  59. XOR Decryption
  60. Prime Pair Sets
  61. Cyclical Figurate Numbers
  62. Cubic Permutations
  63. Powerful Digit Counts
  64. Odd Period Square Roots
  65. Convergents of \(e\)
  66. Diophantine Equation
  67. Maximum Path Sum II
  68. Magic 5-gon Ring
  69. Totient Maximum