math.CO/0409509 number 85

### What is the conjecture
(corrected from paper)
For even $n$, the number of minimax trees with $n$ nodes, $a(2n)$, is $2^n$ times the number of labelled ordered partitions of a $2n$-set into odd parts, that is,

$$
\begin{equation}a(2n) = 2^n\cdot[\frac{x^{2n}}{(2n)!}]\frac{1}{1-\sinh x}.\end{equation}
$$

See https://oeis.org/A080795 and https://oeis.org/A006154 . This seems not too difficult to prove.

### Prerequisites needed

Status: open

### Choose either option
- [ ] I plan on adding this conjecture to the repository
- [X] This issue is up for grabs: I would like to see this conjecture added by somebody else

Start by checking the repository's existing formalized conjecture entries and compare the statement with OEIS A080795 and A006154. Determine how this conjecture should be represented in the repository, and consider the work complete when the corrected minimax-tree formula is added in the established format with its sources recorded.

Written by the indexing model from the issue text.