(7*n^3+4*n^2+4*n)*binomial(2*n,n)/30.

Terms

a(0) =0a(1) =1a(2) =16a(3) =158a(4) =1232a(5) =8358a(6) =51744a(7) =300300a(8) =1661088a(9) =8853702a(10) =45819488a(11) =231499268a(12) =1146562144a(13) =5584082140a(14) =26808586560a(15) =127118807640a(16) =596271746880