a(n) = 5*a(n-1) - 5*a(n-2) - 3*a(n-3).

Terms

a(0) =0a(1) =0a(2) =1a(3) =5a(4) =20a(5) =72a(6) =245a(7) =805a(8) =2584a(9) =8160a(10) =25465a(11) =78773a(12) =242060a(13) =740040a(14) =2253581a(15) =6841525a(16) =20719600a(17) =62629632a(18) =189025585a(19) =569820965a(20) =1716088004a(21) =5164258440a(22) =15531389285a(23) =46687390213a(24) =140287229320a(25) =421405027680