a(n) = Sum_{k=1..floor(n/2)} k^2 * (n-k)^2.

Terms

a(0) =0a(1) =1a(2) =4a(3) =25a(4) =52a(5) =170a(6) =280a(7) =674a(8) =984a(9) =1979a(10) =2684a(11) =4795a(12) =6188a(13) =10164a(14) =12656a(15) =19524a(16) =23664a(17) =34773a(18) =41268a(19) =58333a(20) =68068a(21) =93214a(22) =107272a(23) =143078a(24) =162760a(25) =212303a(26) =239148a(27) =306047a(28) =341852a(29) =430312