12 Days of Christmas
            
                        
                    
                        
                    13th
        
            99 Bottles of Beer
            
                        
                    
                        
                    12th
        
            Arabic to Roman
            
                        
                    
                        
                    14th
        
            brainfuck
            
                        
                    13th13th
        
            Christmas Trees
            
                        
                    
                        
                    19th
        
            Diamonds
            
                        
                    
                        
                    18th
        
            Divisors
            
                        
                    
                        
                    33rd
        
            Emirp Numbers
            
                        
                    
                        
                    19th
        
            Evil Numbers
            
                        
                    
                        
                    24th
        
            Fibonacci
            
                        
                    
                        
                    98th
        
            Fizz Buzz
            
                        
                    9th61st
        
            Happy Numbers
            
                        
                    
                        
                    15th
        
            Leap Years
            
                        
                    
                        
                    56th
        
            Morse Decoder
            
                        
                    
                        
                    11th
        
            Morse Encoder
            
                        
                    
                        
                    12th
        
            Niven Numbers
            
                        
                    
                        
                    36th
        
            Odious Numbers
            
                        
                    
                        
                    19th
        
            Pangram Grep
            
                        
                    
                        
                    17th
        
            Pascal’s Triangle
            
                        
                    
                        
                    28th
        
            Pernicious Numbers
            
                        
                    
                        
                    48th
        
            Poker
            
                        
                    
                        
                    
                        
                    
        
            Prime Numbers
            
                        
                    
                        
                    29th
        
            Quine
            1st
                        
                    77th
        
            Roman to Arabic
            
                        
                    
                        
                    12th
        
            Rule 110
            
                        
                    
                        
                    9th
        
            Seven Segment
            
                        
                    
                        
                    15th
        
            Sierpiński Triangle
            
                        
                    
                        
                    21st
        
            Spelling Numbers
            
                        
                    
                        
                    
                        
                    
        
            λ
            
                        
                    
                        
                    13th
        
            π
            
                        
                    
                        
                    31st
        
            τ
            
                        
                    
                        
                    20th
        
            φ
            
                        
                    
                        
                    22nd
        
            𝑒