Double factorial of even numbers: (2n)!! = 2^n*n!.
A000165
Double factorial of even numbers: (2n)!! = 2^n*n!.
Terms
- a(0) =1a(1) =2a(2) =8a(3) =48a(4) =384a(5) =3840a(6) =46080a(7) =645120a(8) =10321920a(9) =185794560a(10) =3715891200a(11) =81749606400
External references
- oeis: A000165