a(n) = Sum_{k = 0..n} k*binomial(2*n+1, k).

Terms

a(0) =0a(1) =3a(2) =25a(3) =154a(4) =837a(5) =4246a(6) =20618a(7) =97140a(8) =447661a(9) =2028478a(10) =9070110a(11) =40122028a(12) =175913250a(13) =765561564a(14) =3310623412a(15) =14238676712a(16) =60949133949a(17) =259809601870