a(n) = (4*n+1)!/( (2*n+1)! * ((n+1)!)^2 ).
A111911
a(n) = (4*n+1)!/( (2*n+1)! * ((n+1)!)^2 ).
Terms
- a(0) =1a(1) =5a(2) =84a(3) =2145a(4) =68068a(5) =2469012a(6) =98062800a(7) =4159088505a(8) =185392049700
External references
- oeis: A111911
A111911
a(n) = (4*n+1)!/( (2*n+1)! * ((n+1)!)^2 ).