a(n) = (n+1)*(n+2)^2*(n+3)*(n+4)*(5*n^2 + 18*n + 15)/720.

Terms

a(0) =1a(1) =19a(2) =142a(3) =665a(4) =2338a(5) =6762a(6) =16968a(7) =38214a(8) =79035a(9) =152581a(10) =278278a(11) =483847a(12) =807716a(13) =1301860a(14) =2035104a(15) =3096924a(16) =4601781a(17) =6694023a(18) =9553390a(19) =13401157a(20) =18506950a(21) =25196270a(22) =33858760a(23) =44957250a(24) =59037615a(25) =76739481a(26) =98807814a(27) =126105427