From: Convolution identities for twisted Eisenstein series and twisted divisor functions
σ 1 (n)=n
σ 1 ∗ (n)=n
σ 1 (n)=n+2
σ 1 ∗ (n)=n+2
n
1
2 m , m∈N∪{0}
none
n = 2p, with p any odd prime
σ 1 (n)=n+1
σ 1 ∗ (n)=n+1
σ 1 (n)=n+3
σ 1 ∗ (n)=n+3
prime
odd prime
4