Gryszka, K. (2023). The identity 7^(3n)+7^(3n+1)=(2∙7^n )^3 and its generalizations. Annales Universitatis Paedagogicae Cracoviensis | Studia Ad Didacticam Mathematicae Pertinentia, 15, 5–13. https://doi.org/10.24917/20809751.15.1