import arcpy
mxd = arcpy.mapping.MapDocument("CURRENT")
pageNumbers = [4,7,11] #select pages before exporting
    for pageNum in pageNumbers:
    mxd.dataDrivenPages.currentPageID = pageNum
    arcpy.mapping.ExportToJPEG(mxd, r"C:Path" + str(pageNum) + ".jpg")
del mxd