Thank you ,you are smart. I give the total solutions for you.

來源: 於 2010-10-12 10:32:48 [舊帖] [給我悄悄話] 本文已被閱讀：次

a=513+n,b=513+n-1 c=513-n-1 and d=513-n-2.      1<=n<=511