Problems & Puzzles: Problems
2.- Carl Pomerance Observation
5.- Missed prime factors in Woodall numbers
7.- Primes and Parity of x and its inverse x, module p
8.-(m, n+1) and (m+1, n) with the same set of prime factors
9.-Let f(n) be the number of ways of representing n
10.-Find a 500-digit prime p and positive integers x, y
11.-Here you are asked to find primes of the following form (pr - 1)/(pd -1), expressible in more than one way.
12.-Prime producing polynomials
14.-N and N^2-1 powerful numbers
15.-Why the Twin Constant is so close to 2/3?
16.-A little puzzle from Mike Keith (12/12/98)
17.-The largest known sequence of consecutive and reversible primes.
18.- Pi as a concatenation of the smallest contiguous different primes
19.- Divisors (I): The least number N(d) with d number of divisors.
20.- Divisors (II): K consecutive numbers with the same number of divisors.
21.- Divisors (III). Certain questions about s(N), the sum of divisors of a number N.
22.- Divisors (IV) Aliquot sequences, factorizing s1131 (276)
23.- Divisors (V) Aliquot sequences, Sociable Numbers.
25.- The William Paulsen's Prime Numbers Maze
26.- The earliest Cunningham Chains.
27.- Congruent K contiguous products of consecutive numbers.
28.- K least consecutive numbers n such that are not squarefree
30.- A stepladder to Ba sequence
31.- Fibonacci all composites sequence
32.- Fibonacci and permuted all composites sequences
33.- The extreme prime triplets
36.The Liskovets-Gallot numbers
37. The Liu Fengsui's Prime Formula
38. Sebastián Martín Ruiz Prime formulas
39. The primes sequence and the Sebastian's function
42 . Floor Exponent Prime Sequences
44 . Twin-primes producing polynomials race
48. Prime Simple Perfect Squared Rectangles
50. Is there a Cullen prime Cn with n prime ?
53. Powerful numbers revisited
54. AP22 with the difference 43#
57. Carmichael numbers c & 2c+1
59. Wieferich-non-Wilson primes
60. Symmetric primes on each side.
62. Symmetric k-tuples of consecutive primes
63. 3x3 Magic squares composed by triangular numbers.
64. Prime convex quadrilateral
66. Every positive is integer is the sum of 3 palindromes. Looking for another proof.
67. Multigrade Prime Solutions.
70. Set of integers whose sum of any two is a perfect square
72. Consecutive primes inside a 9x9 square such that...
73. Minimal symmetric tuples from consecutive twin primes...
74. Prime Number Polyomino Islands in Consecutive-Odd-Number-Labeled Hilbert Curves
75. The Castillo Toloza, Prime Counting Function, Q(x)
76. More on Egyptian fractions
77. Accumulating primes in a 2-pans balance (A332788)
79. More on Egyptian fractions-II
80. Twin primes generating consecutive...
81. Pythagorean triangles with triangular sides
82. Pythagorean triangles again -II