A sitar string is 0.7 m long, and waves travel along it at 252 m/s.

A string fixed at both ends, or a pipe open at both ends: $f_n = \dfrac{nv}{2L}$, every harmonic. A pipe closed at one end: $f = \dfrac{v}{4L}, \dfrac{3v}{4L}, \dfrac{5v}{4L}, \ldots$, odd harmonics only. Resonance tube: $\lambda = 2(l_2 - l_1)$ and $e = \dfrac{\lambda}{4} - l_1$.