a(n) = 30*binomial(2n,n)/(n+3).

Terms

a(0) =10a(1) =15a(2) =36a(3) =100a(4) =300a(5) =945a(6) =3080a(7) =10296a(8) =35100a(9) =121550a(10) =426360a(11) =1511640a(12) =5408312a(13) =19501125a(14) =70794000a(15) =258529200a(16) =949074300a(17) =3500409330a(18) =12964479000a(19) =48198087000a(20) =179799820200a(21) =672822343050