Constant-one arithmetic function
= Constant-one arithmetic function
{title2=$\mathbf 1$}
The constant-one arithmetic function has $\mathbf 1(n)=1$ for every <positive integer> $n$. Its <Dirichlet convolution> with $f$ is the <divisor sum> $(\mathbf 1*f)(n)=\sum_{d\mid n}f(d)$.