Why is there a larger gap between certain Frets of the Sitar?
If you look at the sitar, you see a larger gap between the 7th (the root note of the scale) and the 8th fret. There is a larger gap between the the 13th (the fifth) and 14th fret as well. This means that the flat 2nd and the flat 6th are missing. These gaps actually make visualizing the notes easier. Since the sitar has such a long neck, it makes identifying the root note and the tonic easy. It is the nature of Indian Classical Music that most raagas are such that both the flat second and the maor second are not used. There are very few raags with both these notes played. If needed the flat second can be played by pulling the string to get the exact note.