Encryption decoding

I have an old encryption style I need to solve.
a "key" is displayed in an encryted form, I need to decode this. This is what I know: The "key" can be +/- 2147483647. I have some keys with there encrypted form:
KEY ENCRYPTION:

1 -626371163
2 447370661
3 -1700112987
4 2057983397
5 -89500251
6 984241573
7 -1163242075
8 1252677029
9 -894806619
10 178935205
-1 -1521112486
-3 -447370662
-5 2057983398
2147483647 -1521112485
-2147483647 -626371164

I can also get the encryted number for any key that may be useful in solving this.