Convert recursion to tail recursion

I have a question about how to convert 'recursion' to 'tail recursion'.

This is not a homework, just a question that popped up when I tried to polish the recursion theorem from a book on algorithms.

I am familiar with the 2 typical examples of using recursion (factorial and Fibonacci sequence), and also know how to implement them in a recursive way and tail-recursive way.

My code is as below (I use Perl just to make it simple, but can be easily converted to C/Java/C++).

# This is the recursive function
sub recP {
    my ($n) = @_;
    if ($n == 0 or $n == 1 or $n == 2) {
        return 1;
    } else {
        return (recP($n-3) * recP($n-1)) + 1;
    }
}

for my $k (1 .. 10) {
    print "recP($k) = ", recP($k), "\n";
}

When running the code, the output as below:

recP(1) = 1
recP(2) = 1
recP(3) = 2
recP(4) = 3
recP(5) = 4
recP(6) = 9
recP(7) = 28
recP(8) = 113
recP(9) = 1018

The recursive function invokes itself twice with different parameters before return. I've tried several ways to convert this to a tail recursive function but all turned out to be wrong.

Can anybody take a look at the code and show me the correct way to make it tail-recursive? Especially I believe there is a routine for the conversion for this tree recursion (invoke recursive function multiple times before return), can anyone shed some light on this? So I can use the same logic to handle different questions later.