a(n) = (n-1)^3*((n-2)^2 - 2*(n-3)).

Terms

a(0) =0a(1) =2a(2) =8a(3) =54a(4) =320a(5) =1250a(6) =3672a(7) =8918a(8) =18944a(9) =36450a(10) =65000a(11) =109142a(12) =174528a(13) =268034a(14) =397880a(15) =573750a(16) =806912a(17) =1110338a(18) =1498824a(19) =1989110a(20) =2600000a(21) =3352482a(22) =4269848a(23) =5377814a(24) =6704640a(25) =8281250a(26) =10141352a(27) =12321558a(28) =14861504a(29) =17803970