Answer:
77
Explanation:
as far as I can tell the steps between the given numbers are
-1
+4
-27
+16
1 can be expressed as 1³
4 can be expressed as 2²
27 can be expressed as 3³
16 can be expressed as 4²
my best guess is that next one is minus 5³ = -125
edit: technically the given steps can be expressed as
(-1)³
(-2)²
(-3)³
(-4)²
somewhat nicer pattern there