| 1 |
The first positive integer |
| 2 |
The only even prime number |
| 3 |
The first odd prime number |
| 4 |
The first nontrivial
perfect square |
| 5 |
The sum of the first two prime numbers |
| 6 |
The first perfect number |
| 7 |
The first double Mersenne prime |
| 8 |
The sum of the first pair of twin primes |
| 9 |
The only positive perfect power that is one more than another |
| 10 |
The sum of the first three prime numbers |
| 11 |
The first two-digit prime number |
| 12 |
The only two-digit Superfactorial |
| 13 |
The first two-digit lucky number |
| 14 |
The first even nontotient |
| 15 |
There are 15 two-sided primes (alt) |
| 16 |
The smallest number with exactly five divisors |
| 17 |
The sum of the first four prime numbers |
| 18 |
The only number where the sum of its digits is its half |
| 19 |
The first non-permutable prime |
| 20 |
Very close to the difference of Gelfond's constant and pi |
| 21 |
The sum of the divisors of the first five positive integers |
| 22 |
There are 22 permutable primes before the prime repunits |
| 23 |
23! (23 factorial) is 23 digits long, along with 22! and 24! |
| 24 |
The only nontrivial solution to the cannonball problem |
| 25 |
The smallest square that is a sum of two non-zero squares |
| 26 |
The smallest even n such that both n+1 and n−1 aren't prime |
| 27 |
The first composite number not divisible by any of its digits |
| 28 |
The sum of the first five prime numbersClick me! |
| 29 |
The sum of three consecutive squares |
| 30 |
The first sphenic number |
| 31 |
The first two-digit self prime |
| 32 |
The first nontrivial fifth power |
| 33 |
The sum of the first four positive factorials |
| 34 |
The magic constant of a normal 4×4 magic square |
| 35 |
The amount of hexominoes |
| 36 |
The first nontrivial square triangular number |
| 37 |
The center of the smallest magic square using only primes and 1 |
| 38 |
The sum of the squares of the first three primes |
| 39 |
The sum of the first three powers of 3 |
| 40 |
The first two-digit refactorable number not divisible by 6 |
| 41 |
The smallest integer whose reciprocal repeats every five digits |
| 42 |
The Answer to the Question of Life, The Universe, and Everything |
| 43 |
The only two-digit term of Sylvester's sequence |
| 44 |
The number of derangements of 5 items |
| 45 |
The sum of all single-digit integers |
| 46 |
The largest even number that is not the sum of 2 abundant numbers |
| 47 |
The third two-digit strictly non-palindromic number |
| 48 |
The smallest number with exactly ten divisors |
| 49 |
In the first two triplets of squares in arithmetic progression |
| 50 |
The first sum of two positive squares in two ways |