Walter Shur. The Last Digit of (2n choose n) and Sigma(n choose i)(2n-2i choose n-i). Electr. J. Comb., 4(2), 1997. [doi]
@article{Shur97, title = {The Last Digit of (2n choose n) and Sigma(n choose i)(2n-2i choose n-i)}, author = {Walter Shur}, year = {1997}, url = {http://www.combinatorics.org/Volume_4/Abstracts/v4i2r16ab.html}, researchr = {https://researchr.org/publication/Shur97}, cites = {0}, citedby = {0}, journal = {Electr. J. Comb.}, volume = {4}, number = {2}, }