a(n) = (n^9 + 5*n^8 + 4*n^7 - n^6 - 5*n^5 + 2*n^4)/6.

Terms

a(0) =0a(1) =1a(2) =352a(3) =9909a(4) =107776a(5) =698125a(6) =3252096a(7) =12045817a(8) =37679104a(9) =103495401a(10) =256420000a(11) =584190541a(12) =1241471232a(13) =2487920149a(14) =4741917376a(15) =8654360625a(16) =15207694336a(17) =25846158097a(18) =42644120544a(19) =68520305701a(20) =107506720000a(21) =165082149981a(22) =248581222912a(23) =367691205289