`nRootedShapes`

and `nUnrootedShapes`

give the number of (un)rooted binary
trees on *n* unlabelled leaves.

## Source

`nRootedShapes`

corresponds to the Wedderburn-Etherington numbers,
OEIS A001190

`nUnrootedShapes`

is OEIS A000672

`nRootedShapes`

and `nUnrootedShapes`

give the number of (un)rooted binary
trees on *n* unlabelled leaves.

`nRootedShapes`

corresponds to the Wedderburn-Etherington numbers,
OEIS A001190

`nUnrootedShapes`

is OEIS A000672