for loop for read different band of image and apply the calcilation on it.

I have large data set of satellite images. seven bands of a one location(tile) are stored in separate tif images. I have the data from 2000 to 2014. for one year there are 46*7 images.all the data are in same folder. following is the format of the data files. 2000_49_band_1, 2000_49_band_2, 2000_49_band_3, 2000_49_band_4, 2000_49_band_5, 2000_49_band_6, 2000_49_band_7,

.................... 2000_57_band_1, 2000_57_band_2, .................... 2000_65_band_1, 2000_65_band_2, .................. 2001_49_band_1, 2001_49_band_2, .................... I Want to do this NDVI_2000_49=((2000_49_band1)-(2000_49_band_2))./((2000_49_band1)-(2000_49_band_2)); NDVI_2000_57=((2000_57_band1)-(2000_57_band_2))./((2000_57_band1)-(2000_57_band_2)); NDVI_2001_49=((2001_49_band1)-(2001_49_band_2))./((2001_49_band1)-(2001_49_band_2)); ................................ I want to automate the procedure. can any one knoe the procedure.