a(n) = (1-n)^(n-1).

Terms

a(0) =1a(1) =1a(2) =-1a(3) =4a(4) =-27a(5) =256a(6) =-3125a(7) =46656a(8) =-823543a(9) =16777216a(10) =-387420489a(11) =10000000000a(12) =-285311670611