a(n) = n^2*(2*n^8 + 120*n^6 + 1806*n^4 + 7180*n^2 + 5067)/14175.

Terms

a(0) =0a(1) =1a(2) =20a(3) =201a(4) =1360a(5) =7001a(6) =29364a(7) =104881a(8) =329024a(9) =927441a(10) =2390004a(11) =5707449a(12) =12767184a(13) =26986089a(14) =54284244a(15) =104535009a(16) =193664256a(17) =346615329a(18) =601446996a(19) =1014889769a(20) =1669752016a(21) =2684641785a(22) =4226553716a(23) =6526963345a(24) =9902174016a(25) =14778775025a(26) =21725194036a(27) =31490462745