[seqfan] Dyck paths with descents restricted by ascents
David Scambler
dscambler at bmm.com
Sun Jan 9 02:35:07 CET 2011
Proposed A179544,
Dyck paths of semi-length n for which the set of ascent lengths and the
set of descent lengths are the same partition of n.
1, 1, 2, 5, 12, 30, 80, 219, 614, 1766, 5206, 15646, 47834, 148602, 468110, ...
e.g.
For n=4 the paths UUUDDUDD and UUDUUDDD fail the definition because {2,2} != {3,1}
so a(4) = 12 rather than equal to Catalan(4)=14
cheers
dave
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