What is the least number of moves needed to solve the k-peg Towers of Hanoi problem?

Roberto Demontis. What is the least number of moves needed to solve the k-peg Towers of Hanoi problem?. Discrete Math., Alg. and Appl., 11(1):1930001, 2019. [doi]

@article{Demontis19,
  title = {What is the least number of moves needed to solve the k-peg Towers of Hanoi problem?},
  author = {Roberto Demontis},
  year = {2019},
  doi = {10.1142/S1793830919300017},
  url = {https://doi.org/10.1142/S1793830919300017},
  researchr = {https://researchr.org/publication/Demontis19},
  cites = {0},
  citedby = {0},
  journal = {Discrete Math., Alg. and Appl.},
  volume = {11},
  number = {1},
  pages = {1930001},
}