Adjacent ratio is a ratio between the frequency of the 2 successive Shrutis.
I worked out the 'Adjacent ratios' between all 22 shrutis and they showed a definite repetitive pattern or a unique formula, with age-old mathematical numbers governing the ratios such as the Pythagoran Limma, and Syntonic Comma.
Let us take Shadja as that of the middle C in the keyboard, with the ET frequency of 261.6255528 Hz (Obtained by dividing 440 by 1.0594631, by 9 times).
Shrutis are based on 3 Successive or Adjacent Ratios as shown below. (Refer to following tables)
Thus the cycle of the chain of adjacent ratios:
The sequence is not haphazard, but has a peculiar design !The values of 1, 2, and 3 are those of the Adjacent Ratios 1, 2, and 3 respectively as given above.