Nowadays, educators often use different computer algebra systems for teaching advanced math topics for CS students, and as a tool for solving math problems and providing research. Computer algebra systems allow the students to practice skills both programming and mathematics, that help to develop main components of computational thinking (decomposition, pattern recognition, abstraction, and algorithms). We provide the example of the of the use one of CAS (Mathematica) for the mathematical research on the D(s)-function associated with Riemann Zeta function. For solving this problem, we need to find the algorithm in order to get a mathematically correct results generated by Mathematica.