Concepts2
∑MathAdvanced
Divisor Function Sums
Summing the divisor function d(i) up to n equals counting lattice points under the hyperbola xy ≤ n, which can be done in O(√n) using floor-division blocks.
#divisor function#euler totient#mobius function+11
∑MathIntermediate
Multiplicative Functions
A multiplicative function is an arithmetic function f with f(mn) = f(m)f(n) whenever gcd(m, n) = 1.
#multiplicative function#dirichlet convolution#mobius function+12