a(n) = binomial(n+5,5) * binomial(n+5,4)/(n+5).

Terms

a(0) =1a(1) =15a(2) =105a(3) =490a(4) =1764a(5) =5292a(6) =13860a(7) =32670a(8) =70785a(9) =143143a(10) =273273a(11) =496860a(12) =866320a(13) =1456560a(14) =2372112a(15) =3755844a(16) =5799465a(17) =8756055a(18) =12954865a(19) =18818646a(20) =26883780a(21) =37823500a(22) =52474500a(23) =71867250a(24) =97260345a(25) =130179231a(26) =172459665a(27) =226296280a(28) =294296640a(29) =379541184