-1, 1, 3, 5, 10
0=1+(-1)
2=3+(-1)
4=3+1
4=5+(-1)
6=5+1
8=5+3
9=10+(-1)
11=10+1
13=10+3
15=10+5
I worked from left to right using trail and error. The first thing i worked out was that 0=1+(-1). Once i had worked this out, i found that to make 2 i must either have another 1 or a 3. Having two of the same number would seem quite pointless, so i decided to take 3. Then to work out 4, i could use my 3 and 1. I still had another 4 to work out and tried to think of a sum with a number that i didn't have and a number that i did have. This came to 4=5+(-1). I then used my 5 to work out the next number in the sequence, 6. For the number 8 i had already got the numbers that i needed to make a sum of 8. Finally i needed one more number, i thought about the numbers i had left and found that i had the unit of the numbers 11, 13, and 15. So all i needed to make these numbers was 10. This means that the sum for 9 would be 9=10+(-1).