a(n) = 140*C(2n,n)/(n+4).

Terms

a(0) =35a(1) =56a(2) =140a(3) =400a(4) =1225a(5) =3920a(6) =12936a(7) =43680a(8) =150150a(9) =523600a(10) =1847560a(11) =6584032a(12) =23661365a(13) =85652000a(14) =312018000a(15) =1142971200a(16) =4207562730a(17) =15557374800a(18) =57750861000a(19) =215145084000a(20) =804104751450