a(n) = sigma((4^n - 1)/3), where sigma(n) is the sum of positive divisors of n.
A102359
a(n) = sigma((4^n - 1)/3), where sigma(n) is the sum of positive divisors of n.
Terms
- a(0) =1a(1) =6a(2) =32a(3) =108a(4) =384a(5) =2688a(6) =5632a(7) =27864a(8) =153920a(9) =499968a(10) =1477440a(11) =11708928a(12) =22380544a(13) =115568640a(14) =620101632a(15) =1826150832a(16) =5726797824a(17) =54044390400a(18) =91626668032a(19) =555102471168
External references
- oeis: A102359