a(n) = binomial(2n,n)*n*(2n+1)/2.

Terms

a(0) =0a(1) =3a(2) =30a(3) =210a(4) =1260a(5) =6930a(6) =36036a(7) =180180a(8) =875160a(9) =4157010a(10) =19399380a(11) =89237148a(12) =405623400a(13) =1825305300a(14) =8143669800a(15) =36064823400a(16) =158685222960a(17) =694247850450