Binomial coefficients C(2n+1, n-2).

Terms

a(0) =1a(1) =7a(2) =36a(3) =165a(4) =715a(5) =3003a(6) =12376a(7) =50388a(8) =203490a(9) =817190a(10) =3268760a(11) =13037895a(12) =51895935a(13) =206253075a(14) =818809200a(15) =3247943160a(16) =12875774670a(17) =51021117810a(18) =202112640600a(19) =800472431850