a(n) = 9*n^3 - 18*n^2 + 10*n.

Terms

a(0) =0a(1) =1a(2) =20a(3) =111a(4) =328a(5) =725a(6) =1356a(7) =2275a(8) =3536a(9) =5193a(10) =7300a(11) =9911a(12) =13080a(13) =16861a(14) =21308a(15) =26475a(16) =32416a(17) =39185a(18) =46836a(19) =55423a(20) =65000a(21) =75621a(22) =87340a(23) =100211a(24) =114288a(25) =129625a(26) =146276a(27) =164295a(28) =183736a(29) =204653