a(n) = Sum_{j=0..n} (2*n)!/(2*n-j)!.
A066211
a(n) = Sum_{j=0..n} (2*n)!/(2*n-j)!.
Terms
- a(0) =1a(1) =3a(2) =17a(3) =157a(4) =2081a(5) =36101a(6) =773665a(7) =19726085a(8) =582913217a(9) =19582414021a(10) =736891600001
External references
- oeis: A066211