Abstract:
The result of V.A. Bykovsky and M.D. Monina on the distribution of integer points on the three-dimensional sphere $ a_1^2 + a_2^2 + a_3^2 + a_4^2 = d $ with odd $d$ is extended to the case of even $d.$
Key words:integral points on a sphere, modular functions, Hecke series.