12 Days of Christmas
9th
99 Bottles of Beer
13th
Arabic to Roman
7th
Christmas Trees
11th
Divisors
33rd
Emirp Numbers
12th
Evil Numbers
21st
Fibonacci
56th
Fizz Buzz
82nd
Happy Numbers
10th
Niven Numbers
44th
Odious Numbers
21st
Pascal’s Triangle
15th
Pernicious Numbers
22nd
Prime Numbers
37th
Quine
1st
Roman to Arabic
10th
Seven Segment
10th
Sierpiński Triangle
9th
π
11th