a(n) = sigma((10^n - 1)/9), where sigma(n) is the sum of positive divisors of n.
A103759
a(n) = sigma((10^n - 1)/9), where sigma(n) is the sum of positive divisors of n.
Terms
- a(0) =1a(1) =12a(2) =152a(3) =1224a(4) =11424a(5) =204288a(6) =1116000a(7) =12499488a(8) =164831992a(9) =1246404096a(10) =11111646000a(11) =206331697152
External references
- oeis: A103759