-1
-2 = -1^1 - |-1|
3 = -2^2 - (|-2|*|-1|)
21 = 3^3 - (|3|*|-2|*|-1|)
194355 =21^4-(|21|*|3|*|-2|*|-1|)
A1=-1
n>=2
An=An-1^(n-1)-(|An-1|*|An-2|*...*|A1|)