a(0) = 0; a(n) = C(2*n-2,n-1)*(n^2-2*n+2)/n for n >= 1.

Terms

a(0) =0a(1) =1a(2) =2a(3) =10a(4) =50a(5) =238a(6) =1092a(7) =4884a(8) =21450a(9) =92950a(10) =398684a(11) =1696396a(12) =7171892a(13) =30161740a(14) =126293000a(15) =526864680a(16) =2191034970a(17) =9086921190a(18) =37596989100a(19) =155232577500a(20) =639749274780