The first time you talk about the decryption key you say it's 1092. Shouldn't it be 3492?

@OlivierGrégoire of course C# isn't competitive, but it can be among other answers in C#, I just wanted recursive functions to have the same treatment as non-recursive ones. In the question linked, someone who writes the non-recursive version will win against the recursive one because of what CAD97 proposes, even though the recursive version should win as it is shorter to write. I hope this doesn't sound as a tantrum... :-)

Taking into account that C# can only compete with other answers in C# (it is silly to try to compete against Jelly or other similar languages), what if C# just get its own set of rules? Do we really need to make the rules the same for every language?

I understand your point of view, but then if non-recursive functions can be expressed as lambda expressions and recursive functions cannot, this penalises these answers so people will just stop writing recursive functions in C#, which can be in fact shorter and more elegant than their non-recursive counterparts. How then can we make the competition between recursive and non-recursive functions in C# a fair one?