The following special case of a conjecture by Loehr and Warrington was proved recently by Ekhad, Vatter. and Zeilberger:
There are 10(n) zero-sum words of length 5n in the alphabet {+3, -2} such that no zero-sum consecutive subword that starts with +3 may be followed immediately by -2.
We give a simple bijective proof of the conjecture in its original and more general setting. To do this we reformulate the problem in terms of cylindrical lattice walks. (c) 2005 Elsevier Ltd. All rights reserved.