1048645

Appears in sequences

• a(n) = Sum_{ k, k|n } 2^(k-1).at n=20A034729
• a(n) = (-1)^(n+1) * coefficient of x^n in Sum_{k>=1} x^k/(1+2*x^k).at n=20A081295
• a(n) = Sum_{d|n} (-1)^(d-1) * 2^(n/d-1).at n=20A373275