12 Days of Christmas
8th
99 Bottles of Beer
6th
Abundant Numbers
26th
Christmas Trees
5th
CSS Colors
5th
Diamonds
5th
Divisors
10th
Emirp Numbers
Fibonacci
43rd
Fizz Buzz
26th489th1,427th
Happy Numbers
31st
Intersection
3rd
Leap Years
12th
Morse Decoder
3rd
Morse Encoder
4th
Niven Numbers
30th
Prime Numbers
33rd
Seven Segment
5th
Sierpiński Triangle
11th
Tongue-twisters
17th
United States
7th