Request translation into Perl

I'm testing something, and I'm stuck trying to write a Perl equivalent of this function because Perl's syntax is made of ugly, rudimentary, hack and fail. Could you please show me how to do this very simple thing in Perl?

function f($i = 1, $r = 17) {
    return --$r <= 0 ? null : array($i => f($i + 2, $r), $i + 1 => f($i + 3, $r));
}
Thanks!

Oh, and your implementation is silly. It's exactly the same sort of silliness as a naive implementation of good old fibonacci. Recursion is great and all but you have to learn when not to use it.