a(n) = 5*(n+1)*binomial(n+4,5)/2.

Terms

a(0) =5a(1) =45a(2) =210a(3) =700a(4) =1890a(5) =4410a(6) =9240a(7) =17820a(8) =32175a(9) =55055a(10) =90090a(11) =141960a(12) =216580a(13) =321300a(14) =465120a(15) =658920a(16) =915705a(17) =1250865a(18) =1682450a(19) =2231460a(20) =2922150a(21) =3782350a(22) =4843800a(23) =6142500a(24) =7719075a(25) =9619155a(26) =11893770a(27) =14599760a(28) =17800200a(29) =21564840