a(n) = n!*Sum_{k=0..n/2} n^(2k)/(2k)!.
A046707
a(n) = n!*Sum_{k=0..n/2} n^(2k)/(2k)!.
Terms
- a(0) =1a(1) =1a(2) =6a(3) =33a(4) =472a(5) =4745a(6) =99216a(7) =1456273a(8) =39669120a(9) =769528593a(10) =25737068800a(11) =622548099041
External references
- oeis: A046707