a(n) = 20*C(2n,n)*(2n+1)/(n+4).

Terms

a(0) =5a(1) =24a(2) =100a(3) =400a(4) =1575a(5) =6160a(6) =24024a(7) =93600a(8) =364650a(9) =1421200a(10) =5542680a(11) =21633248a(12) =84504875a(13) =330372000a(14) =1292646000a(15) =5061729600a(16) =19835652870a(17) =77786874000a(18) =305254551000