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Problems


IDDescription / Title
1
Multiples of 3 and 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 canceling 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