Binomial coefficient C(5n,n-4).

Terms

a(0) =1a(1) =25a(2) =435a(3) =6545a(4) =91390a(5) =1221759a(6) =15890700a(7) =202927725a(8) =2558620845a(9) =31966749880a(10) =396704524216