a(n) = (n+1)*(n+2)*(n+3)*(n+4)*(19*n^2 + 47*n + 30)/720.

Terms

a(0) =1a(1) =16a(2) =100a(3) =399a(4) =1218a(5) =3108a(6) =6972a(7) =14190a(8) =26763a(9) =47476a(10) =80080a(11) =129493a(12) =202020a(13) =305592a(14) =450024a(15) =647292a(16) =911829a(17) =1260840a(18) =1714636a(19) =2296987a(20) =3035494a(21) =3961980a(22) =5112900a(23) =6529770a(24) =8259615a(25) =10355436a(26) =12876696a(27) =15889825a(28) =19468744a(29) =23695408