# Find the well-known Christmas song

14 25 15 9 3 7 2 6 4 7 2 9 1 1 14 25 15 9 3 7 2 6 4 7 2 9 1 1 2 15 26 19 1 4 16 1 7 4 9 1 7 14 8 5 25 15 4 5 13 3 5 13 14 25 15 9 3 7 2 6 4 7 2 9 1 1 14 25 15 9 3 7 2 6 4 7 2 9 1 1 2 15 26 19 1 4 16 1 7 4 9 1 7 14 8 5 25 15 4 5 13 3 5 13 5 14 2 14 5 19 26 13 9 1 1 5 10 15 1 5 7 8 6 6 1 9 7 15 1 9 1 23 8 2 4 19 7 14 10 15 1 5 2 3 7 25 14 19 11 4 5 11 11 9 1 4 9 14 25 15 9 3 7 2 6 4 7 2 9 1 1 14 25 15 9 3 7 2 6 4 7 2 9 1 1 2 15 26 19 1 4 16 1 7 4 9 1 7 14 8 5 25 15 4 5 13 3 5 13

Yes, this is a Christmas song. It's never too early for Christmas, right? Only a couple steps and, bam, you've decoded this! Just don't rush it.

You may or may not be able to decipher the name of this song just by looking at the pattern; no, that's not enough, please explain how you came to this conclusion. Oh, and the solution isn't a mapping like "14 → A, 25 → Q, ..."! The chosen numbers are significant, e.g. you can't swap the 14s and 25s.

Hint 1:

See this tag? I don't think I picked that randomly, no... but, just one question: WHAT IS THE CIPHER?

• For the record, this is not a bad puzzle at all. My downvote comes purely from having sworn a blood oath to combat every single christmas-y thing that rears its ugly head before halloween.
– Bass
Oct 30, 2018 at 21:09
• Ok, I upvoted it, coz just not that bad for that low mark... Oct 30, 2018 at 23:29
• @OmegaKrypton Doesn't matter, that's usually frowned upon (upvoting to bring the score higher). Oct 31, 2018 at 6:03

The numbers are

the Morse Code tree, read left to right, layer by layer. For instance, 1 is E, 2 is T, 3 is I, 4 is A... This is still a mapping from numbers to letters though, even though the question claims it is not: it's just a mapping that can be represented with an extra step through Morse code.

As Excited Raichu found, the lyrics are to

the song "O Christmas Tree".

Alright, this cipher has a few layers.

First,

we gotta A1Z26 it, to get
n y o i c g b f d g b i a a n y o i c g b f d g b i a a b o z s a d p a g d i a g n h e y o d e m c e m n y o i c g b f d g b i a a n y o i c g b f d g b i a a b o z s a d p a g d i a g n h e y o d e m c e m e n b n e s z m i a a e j o a e g h f f a i g o a i a w h b d s g n j o a e b c g y n s k d e k k i a d i n y o i c g b f d g b i a a n y o i c g b f d g b i a a b o z s a d p a g d i a g n h e y o d e m c e m

Then,

I plugged this into a substitution decoder, which coughed up:
o c h r i s t m a s t r e e o c h r i s t m a s t r e e t h y l e a v e s a r e s o u n c h a n g i n g o c h r i s t m a s t r e e o c h r i s t m a s t r e e t h y l e a v e s a r e s o u n c h a n g i n g n o t o n l y g r e e n w h e n s u m m e r s h e r e b u t a l s o w h e n t i s c o l d a n d d r e a r o c h r i s t m a s t r e e o c h r i s t m a s t r e e t h y l e a v e s a r e s o u n c h a n g i n g

using the key

abcdefghijklmnopqrstuvwxyz
dwykavmocutsfenxligbhpjrzq

Now we have to do the most important step: make sure it isn't just a substitution cipher.

We have to decode it using the amazing Vigenere key "aaaaaaaaaaaaaaaaaaaaaaaaa". Any number of 'a's works, but I chose 25 because I felt like it.

Alright, cool.

Seem familiar? Yeah, we can split this into words to get:
o christmas tree o christmas tree thy leaves are so unchanging o christmas tree o christmas tree thy leaves are so unchanging not only green when summers here but also when tis cold and drear o christmas tree thy leaves are so unchanging

These are the lyrics to the Christmas song "O Christmas Tree".

• As I said in the puzzle, the solution isn't just a mapping (which this answer essentially describes). Oct 30, 2018 at 16:04
• @Ekons Are you saying the lyrics exposed by the substitution decoder are not the ones you intended, or are you just disappointed that the method used in the solution is not the one you wanted? Oct 30, 2018 at 16:21
• @IanMacDonald The question explicitly reads that you need to provide the method, and that the method isn't a mapping from numbers to letters (well, this solution is technically letters to letters, but it's essentially the same). Oct 30, 2018 at 16:23
• @EKons I don't understand what method I'm supposed to provide- my solution was using the A1Z26 cipher and then using a substitution cipher decoder. Oct 30, 2018 at 16:24
• @EKons so, under your rules for the answer, someone (not me, too much effort) could just come up with some overly long Vigenere key that decoded it A1Z26ed into any Christmas song they wanted, and you’d accept it? doesn’t that make the question too broad? Oct 30, 2018 at 16:47

A simple conversion to letters of the alphabet reveals: