a(n) = n^2*binomial(n,2).

Terms

a(0) =0a(1) =4a(2) =27a(3) =96a(4) =250a(5) =540a(6) =1029a(7) =1792a(8) =2916a(9) =4500a(10) =6655a(11) =9504a(12) =13182a(13) =17836a(14) =23625a(15) =30720a(16) =39304a(17) =49572a(18) =61731a(19) =76000a(20) =92610a(21) =111804a(22) =133837a(23) =158976a(24) =187500a(25) =219700a(26) =255879a(27) =296352a(28) =341446a(29) =391500