Christian Krattenthaler, Thomas W. Müller. Equations in finite semigroups: explicit enumeration and asymptotics of solution numbers. Journal of Combinatorial Theory, Series A, 105(2):291-334, 2004. [doi]
@article{KrattenthalerM04,
title = {Equations in finite semigroups: explicit enumeration and asymptotics of solution numbers},
author = {Christian Krattenthaler and Thomas W. Müller},
year = {2004},
doi = {10.1016/j.jcta.2003.12.001},
url = {http://dx.doi.org/10.1016/j.jcta.2003.12.001},
researchr = {https://researchr.org/publication/KrattenthalerM04},
cites = {0},
citedby = {0},
journal = {Journal of Combinatorial Theory, Series A},
volume = {105},
number = {2},
pages = {291-334},
}