a(n) = sigma((7^n - 1)/6), where sigma(n) is the sum of positive divisors of n.
A102360
a(n) = sigma((7^n - 1)/6), where sigma(n) is the sum of positive divisors of n.
Terms
- a(0) =1a(1) =15a(2) =80a(3) =961a(4) =2802a(5) =52800a(6) =142020a(7) =2347506a(8) =10512320a(9) =96837120a(10) =329849040a(11) =8619170560a(12) =16148168402a(13) =221483030400
External references
- oeis: A102360