a(n) = -4*((n-1)*(n+1)^(n+1)+1)/(((-1)^n-3)*n^3).
A221740
a(n) = -4*((n-1)*(n+1)^(n+1)+1)/(((-1)^n-3)*n^3).
Terms
- a(0) =1a(1) =7a(2) =19a(3) =293a(4) =1493a(5) =38127a(6) =293479a(7) =10593529a(8) =109739369a(9) =5135610071a(10) =66987982331
External references
- oeis: A221740