a(n) = Sum_{r=1..n} r^4*binomial(n,r)^2.

Terms

a(0) =0a(1) =1a(2) =20a(3) =234a(4) =2144a(5) =16750a(6) =117432a(7) =761460a(8) =4654848a(9) =27173718a(10) =152867000a(11) =834212236a(12) =4438175040a(13) =23108423884a(14) =118111709744a(15) =594059985000