# Thread: Looking for a function

1. ## Looking for a function

I want a mathematical function (floor/ceiling etc. are fine but not piecewise) which does the following:
If the input is odd, just return that number i.e f(2n+1) = 2n+1
If the input is even return the odd number one less than it i.e f(2n) = 2n-1

So for example f(4)=3, f(3)=3

2. Originally Posted by Mr_Random_Guy
I want a mathematical function (floor/ceiling etc. are fine but not piecewise) which does the following:
If the input is odd, just return that number i.e f(2n+1) = 2n+1
If the input is even return the odd number one less than it i.e f(2n) = 2n-1

So for example f(4)=3, f(3)=3
Did you read our guidelines at

https://www.freemathhelp.com/forum/t...l=1#post433156

Hint: $n \in \mathbb Z \implies n - 2 * \left \lfloor \dfrac{n}{2} \right \rfloor = \text {WHAT?}.$

EDIT: This question came up in pre-algebra? That is where it is posted!

3. No I hadn't, thank you. Am in college, although this question is entirely unrelated to anything I'm currently doing. Thanks for the hint, got it.

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