a(n) = (4/45)*n*(n - 2)*(n - 1)*(n^3 - 12*n^2 + 47*n - 15).

Terms

a(0) =0a(1) =0a(2) =0a(3) =24a(4) =96a(5) =240a(6) =544a(7) =1288a(8) =3136a(9) =7392a(10) =16320a(11) =33528a(12) =64416a(13) =116688a(14) =200928a(15) =331240a(16) =525952a(17) =808384a(18) =1207680a(19) =1759704a(20) =2508000a(21) =3504816a(22) =4812192a(23) =6503112a(24) =8662720a(25) =11389600a(26) =14797120a(27) =19014840a(28) =24189984a(29) =30488976