Bias (Series)

The bias of a Series is defined as

$$Q[a_i, a_{i+1}, a_{i+2}]\equiv {a_i a_{i+2}-{a_{i+1}}^2\over a_i a_{i+1} a_{i+2}}.$$

A Series is Geometric Iff $Q=0$. A Series is Artistic Iff the bias is constant.

See also Artistic Series, Geometric Series

References

Duffin, R. J. ``On Seeing Progressions of Constant Cross Ratio.'' Amer. Math. Monthly 100, 38-47, 1993.