a(n) = n^4 - 6*n^3 + 12*n^2 - 4*n + 1.

Terms

a(0) =1a(1) =4a(2) =9a(3) =16a(4) =49a(5) =156a(6) =409a(7) =904a(8) =1761a(9) =3124a(10) =5161a(11) =8064a(12) =12049a(13) =17356a(14) =24249a(15) =33016a(16) =43969a(17) =57444a(18) =73801a(19) =93424a(20) =116721a(21) =144124a(22) =176089a(23) =213096a(24) =255649a(25) =304276a(26) =359529a(27) =421984a(28) =492241a(29) =570924