[seqfan] Re: Question on A001761

[Peter Luschny]

>From Beineke/Pippert: "A triangulation of a convex polygon [and] a
disk dissection [...] can be considered equivalent objects."

Since A001761(n) = n!*Catalan(n) the connection to Euler's
'Betrachtungen, auf wie vielerley Arten
ein gegebenes polygonum durch Diagonallinien in triangula zerschnitten
werden könne' (from a comment in A000108) becomes with an appropriate
definition of 'equivalent' evident.

The story is nicely told in
http://www.mathnet.or.kr/real/2010/01/OtfriedCheong(0112).pdf

Peter