a(n) = 4*n*Catalan(n)^2.

Terms

a(0) =0a(1) =4a(2) =32a(3) =300a(4) =3136a(5) =35280a(6) =418176a(7) =5153148a(8) =65436800a(9) =851005584a(10) =11284224640a(11) =152054927024