OJ Board

It's looks alike a math problem
But I can't find any recurrsion equation
Could someone give me a hint?

I have found a very complex recursion method.But it's too slow,
and I got time limit exceeded during the contest (In the contest,time is 4 seconds).
Now I submitted in the judge and got Accepted(with the
longest time of 8+seconds.)
I also want to know the most brief recursion.

And I think the limit of 16 and 32 are too big,
as a less-200-digit answer for n==2,d should be less than 13.
If n is larger the d is smaller!
d==32 will only occur when n==1.

Thanks.

And I think the limit of 16 and 32 are too big,
as a less-200-digit answer for n==2,d should be less than 13.
If n is larger the d is smaller!
d==32 will only occur when n==1.

The problem assumed that the nodes of each situation would be less than

or equal to 1024.

So the limit of answer is still 200 digits.