[seqfan] Re: Dyck paths with no consecutive peaks/valleys at the same height

Emeric Deutsch deutsch at poly.edu
Mon Nov 8 13:29:04 CET 2010

> First count, regarding no consecutive valleys at the
same height is OK. Bivariate g.f. G=G(t,z) for the 
statistic "number of consecutive valleys at the same 
height" (marked by t) is aG^2-bG+c=0, where a=z(1-z), 
b=(1-z)(1+z-tz), c=1-tz. 
I'll try to work out the other two cases.

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