On the assumption that the E12 values were chosen to be equally spaced *logarithmically* between 10 and 100 ohms we get the ideal values of:

* 10.00
* 12.12
* 14.68
* 17.78
* 21.54
* 26.10
* 31.62
* 38.31
* 46.42
* 56.23
* 68.13
* 82.54
* 100.00

Therefore: the nominal value of 27 ohms is 3.442% higher than the ideal,
and the nominal value of 33 ohms is 4.355% higher than the ideal.

They could have chosen 26 and 32 ohms, respectively: the nominal value of 26 ohms is 0.329% lower than the ideal, and the nominal value of 32 ohms is 1.193% higher than the ideal.

This would have kept all the values within roughly 2% of the ideal values, so I wonder: why do we use the values we all know and love instead?