12 Days of Christmas
28th
52nd80th
35th
99 Bottles of Beer
81st
41st
Abundant Numbers
41st
Christmas Trees
39th
Divisors
64th
Emirp Numbers
63rd
Evil Numbers
69th
Fibonacci
180th
Fizz Buzz
601st1,616th235th389th
154th372nd
Happy Numbers
39th
Leap Years
68th
64th
Odious Numbers
62nd
Pascal’s Triangle
71st
Pernicious Numbers
66th
Prime Numbers
102nd
Quine
703rd
Rock-paper-scissors-Spock-lizard
12th
Sierpiński Triangle
34th
Smith Numbers
24th
18th
United States
11th
Vampire Numbers
19th
λ
18th
π
27th
37th
τ
59th
23rd
φ
42nd
27th
√2
24th
𝑒
57th