The sum problem

Given a sequence 1,2,3,…N, your job is to calculate all the possible sub-sequences that the sum of the sub-sequence is M.
Input
Input contains multiple test cases. each case contains two integers N, M( 1 <= N, M <= 1000000000).input ends with N = M = 0.
Output
For each test case, print all the possible sub-sequence that its sum is M.The format is show in the sample below.print a blank line after each test case.
Sample Input
20 10
50 30
0 0
Sample Output
[1,4]
[10,10]

[4,8]
[6,9]
[9,11]
[30,30]

最后目前还没写出来的一道题，具体思路是：
运用等差数列的公式(n+(n+d))(d/2)=m
化简后是2dn+d+dd=2m。