a(n) = 4^n*(2*n+1)!*(n!)^2/(n+1).A010053a(n) = 4^n*(2*n+1)!*(n!)^2/(n+1).Terms a(0) =1a(1) =12a(2) =2560a(3) =2903040a(4) =10701766656External referencesoeis: A010053