a(n) = (n^2)!/(n!)^(n+1)/(2n-1).A076181a(n) = (n^2)!/(n!)^(n+1)/(2n-1).Terms a(0) =1a(1) =1a(2) =56a(3) =375375a(4) =577185873264External referencesoeis: A076181