# [05AB1E](http://github.com/Adriandmen/05AB1E), 3 bytes, [cracked](https://codegolf.stackexchange.com/a/77444/48934)

Output:

 a(9) = 165
 a(10) = 220

Hidden code:

 ##O

[Try it online](http://05ab1e.tryitonline.net/#code=IyNP&input=NQ) might come in handy.