P596
projecteuler.net

Number of Lattice Points in a Hyperball

ℹ️Published on Sunday, 26th March 2017, 04:00 am; Solved by 404;
Difficulty rating: 50%

Let $T(r)$ be the number of integer quadruplets $x, y, z, t$ such that $x^2 + y^2 + z^2 + t^2 \le r^2$. In other words, $T(r)$ is the number of lattice points in the four-dimensional hyperball of radius $r$.

You are given that $T(2) = 89$, $T(5) = 3121$, $T(100) = 493490641$ and $T(10^4) = 49348022079085897$.

Find $T(10^8) \bmod 1000000007$.



Soluzione

Last modified: May 01, 2025. Website built with Franklin.jl and the lovely Julia programming language.