1. Decomposing into primes

  2. Different ways of defining primes
  3. (-a) × (-a) = a × a
  4. Is it a pleasing number?
  5. Be as fair as possible
  6. Raise integer x to power x, without exponentiation built-ins

  7. Greatest Common Divisor
  8. What is the simplest reversible circuit that computes conjugacy of transpositions

  9. Sum of all integers from 1 to n
  10. Count of relatively prime partitions

  11. Make a Plain PIE!

  12. Delete the first periodic digit

  13. One OEIS after another

  14. Intersection of two triangles
  15. Coprimes up to N

  16. Characteristic polynomial
  17. Collatz Conjecture (OEIS A006577)

  18. Count number of hefty decimals between 2 numbers

  19. Generate Pascal's triangle
  20. Calculate the lowest number where the sum of the sequence of numbers exceeds a given value
  21. Prove me wrong!

  22. Discrete Convolution or Polynomial Multiplication

  23. Stock Time Machine
  24. The working time calculator

  25. Find a Fixed Point

  26. compute number of 1 bits in a binary representation of a number
  27. GolfScript - The missing function

  28. Bitwise GCD Challenge
  29. Finding limits of functions
  30. It's a Slippery Slope
  31. Ascending matrix
  32. Normalize a Vector
  33. BigNum Bakeoff Reboot
  34. Implement hyperexponentiation/tetration without the use of '^'
  35. Count without 3
  36. Iterated phi sequence

  37. Multiply two numbers
  38. Advent Challenge 7: Balance the storage carts!

  39. The sequence of self-contained numbers
  40. Half-Exponential Function
  41. Novel Prime Factors of Repunits
  42. Find the smallest number of participants with resulting percentages

  43. Operations on Sets

  44. 2 factors factorization

  45. Shortest terminating program whose output size exceeds Graham's number
  46. Golf a number bigger than TREE(3)

  47. Proper Divisor mash-up
  48. Draw diagonal positions of me squared

  49. Fastest algorithm for decomposing a perfect power
  50. Simplify a square root

  51. In which number set do I belong?
  52. Divide a number by 3 without using *, /, +, -, % operators

  53. cool untitled sequence thingy

  54. Angle between the hands on a clock
  55. Is my triangle right?

  56. Implement BCD Arithmetic

  57. An Array of Challenges #3: Moving Averages

  58. Digitangular numbers
  59. The sequence of range-exponentiated integers

  60. Minimal sparse rulers

  61. How much present did you get for Christmas?

  62. Yo boy, must it sum

  63. Help me carry my shopping bags

  64. Too Fast, Too Fourier: FFT Code Golf

  65. Determinant of an Integer Matrix
  66. Compute the Lambert W function
  67. What is the standard scratch?

  68. Form tiles in a rectangular ring
  69. Make the largest infinity that you can!

  70. Given an int input n, print out n*reversed(n)

  71. Output the sign

  72. Superstitious hotel elevator

  73. Alternating Sign Sequence

  74. Additive Persistence

  75. The Median of Practically Recreational Languages

  76. Find the coefficients of a rational generating function

  77. Is it a completely even number?
  78. Plus one sheep minus one sheep
  79. Egyptian Fractions

  80. Rotate a hypercube

  81. Pandigital Doubling

  82. The cyclic sequence of even digits, with odds in between

  83. Simple integer operation calculator

  84. Generate the group table for Z_n
  85. On the edges of the hypercube
  86. Programming Languages Through The Years
  87. Verify Topology
  88. Bijective function ℤ → ℤⁿ

  89. LaTeX truth tables
  90. n-th term of the rise & reset sequence

  91. Transmit Pi... precisely

  92. Summation from a to b

  93. Number of values between input and next highest square

  94. set intersection of two lists
  95. Evaluate the binomial theorem!

  96. Pentagonal numbers made from pentagonal numbers
  97. matrix determinant

  98. Find the intersection point of a plane and ray
  99. Factorials and never ending cycles!

  100. Is this number a repdigit?