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

Terms

a(0) =2a(1) =10a(2) =48a(3) =222a(4) =1000a(5) =4420a(6) =19264a(7) =83062a(8) =355128a(9) =1508028a(10) =6368032a(11) =26765420a(12) =112053968a(13) =467531272a(14) =1945009408a(15) =8070882982a(16) =33414977368a(17) =138067832332a(18) =569466322528