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Problems


IDDescription / TitleSolved By
1Multiples of 3 and 5
365072
2Even Fibonacci numbers
301796
3Largest prime factor
220488
4Largest palindrome product
200787
5Smallest multiple
214328
6Sum square difference
215963
710001st prime
184976
8Largest product in a series
164270
9Special Pythagorean triplet
162109
10Summation of primes
148471
11Largest product in a grid
111771
12Highly divisible triangular number
101039
13Large sum
107610
14Longest Collatz sequence
105525
15Lattice paths
87829
16Power digit sum
110338
17Number letter counts
72603
18Maximum path sum I
71194
19Counting Sundays
65666
20Factorial digit sum
100764
21Amicable numbers
70619
22Names scores
65930
23Non-abundant sums
49574
24Lexicographic permutations
57062
251000-digit Fibonacci number
77159
26Reciprocal cycles
40632
27Quadratic primes
42864
28Number spiral diagonals
56931
29Distinct powers
51367
30Digit fifth powers
54647
31Coin sums
40378
32Pandigital products
34764
33Digit canceling fractions
35906
34Digit factorials
47710
35Circular primes
43615
36Double-base palindromes
46415
37Truncatable primes
36910
38Pandigital multiples
31338
39Integer right triangles
36271
40Champernowne's constant
40647
41Pandigital prime
33986
42Coded triangle numbers
38959
43Sub-string divisibility
28856
44Pentagon numbers
27818
45Triangular, pentagonal, and hexagonal
36951
46Goldbach's other conjecture
29595
47Distinct primes factors
28445
48Self powers
61600
49Prime permutations
28147
50Consecutive prime sum
30328