D.V. Plaksin1, T.E. Badokina2, E.V. Shchennikova3

1–3 Federal State Budgetary Educational Institution of Higher Education “National Research Mordovia State University” (Saransk, Russia)
1dmitriy.plaksin1@yandex.ru; 2badokinate@math.mrsu.ru; 3schennikova8000@yandex.ru