a(n) = n^4 - n^3 - n^2 - n.

Terms

a(0) =0a(1) =-2a(2) =2a(3) =42a(4) =172a(5) =470a(6) =1038a(7) =2002a(8) =3512a(9) =5742a(10) =8890a(11) =13178a(12) =18852a(13) =26182a(14) =35462a(15) =47010a(16) =61168a(17) =78302a(18) =98802a(19) =123082a(20) =151580a(21) =184758a(22) =223102a(23) =267122a(24) =317352a(25) =374350a(26) =438698a(27) =511002a(28) =591892a(29) =682022