等差数列
a+3a+5a+7a+……+2013a=（a+2013a）X((2013-1)/2+1)/2=1006X1007a
2a+4b+6a+8b+……+2012b
=2a+6a+...+2010a+4b+8b+...+2012b
=(2a+2010a)X((2010-2)/4+1)/2+(4b+2012b)X((2012-4)/4+1)/2
=1006X503a+1007x503b
(a+3a+5a+7a+……+2013a）-（2a+4b+6a+8b+……+2012b）
=1006X1007a-(1006X503a+1007x503b)
=1006x504a-1007x503b
=507024a-506521