12 Days of Christmas
23rd
Abundant Numbers
25th
31st
Divisors
1st
4th
Emirp Numbers
143rd
72nd
Evil Numbers
303rd
52nd
Fibonacci
131st
7th
Fizz Buzz
28th
3rd
Happy Numbers
133rd
25th
Leap Years
172nd
39th
Look and Say
30th
8th
Niven Numbers
146th
23rd
Odious Numbers
216th
42nd
Pangram Grep
20th
Pernicious Numbers
252nd
46th
Prime Numbers
120th
23rd
Quine
1st
79th
52nd
18th
59th
RecamΓ‘n
177th
14th
Roman to Arabic
35th
Ο
24th