#include #include using namespace std; using ll = long long; using mint = atcoder::modint998244353; template struct csr { using itr = typename std::vector::iterator; struct Node { itr st, en; itr begin() { return st; } itr end() { return en; } int size() { return en - st; } T operator[](int p){ return st[p]; } }; const int N; std::vector start; std::vector E; std::vector> edge; csr(int n) : N(n), start(n + 1) {} void add_edge(int u, T v){ assert(0 <= u && u < N); start[u + 1]++; edge.emplace_back(u, v); } void build(){ E.resize(edge.size()); for(int i = 0; i < N; i++) start[i + 1] += start[i]; auto cnt = start; for(auto [u, v] : edge) E[cnt[u]++] = v; } Node operator[](int p) { return Node{E.begin() + start[p], E.begin() + start[p + 1]}; } }; array,2025> binom; int main(){ ios::sync_with_stdio(false); cin.tie(0); binom[0][0] = 1; for(int i = 1; i < 2025; i++){ binom[i][0] = mint::raw(1); for(int j = 1; j <= i; j++){ binom[i][j] = binom[i - 1][j] + binom[i - 1][j - 1]; } } constexpr int r = 202500; csr divs(r + 1); for(int i = 1; i <= r; i++){ for(int j = i, cur = 1; j <= r; j += i, cur++){ divs.add_edge(j, cur); } } divs.build(); int T; cin >> T; while(T--){ int n, a; cin >> n >> a; mint ans; n--; for(auto ad : divs[a]){ int v = ad - n; if(v % 2 != 0 || v > 0) continue; v = -v / 2; if(v <= n) ans += binom[n][v]; v += ad + 1; if(v <= n) ans -= binom[n][v]; } cout << ans.val() << '\n'; } }