a(n) = (3^(n+1)-1)*n!/2.
A052577
a(n) = (3^(n+1)-1)*n!/2.
Terms
- a(0) =1a(1) =4a(2) =26a(3) =240a(4) =2904a(5) =43680a(6) =786960a(7) =16531200a(8) =396789120a(9) =10713669120a(10) =321413702400
External references
- oeis: A052577
A052577
a(n) = (3^(n+1)-1)*n!/2.