For those unwilling to click-through, it essentially posits an alternate history where infinite series were explored by mathematicians before geometry, so rather than being surprised that the 'circle constant' is found in many infinite series, we would instead be surprised that the 'infinite series constant' is found in the geometry of a circle.
Pi is the scaling factor of the diameter of a circle to its circumference; there's an infinite set of such scaling factors: one for each ellipse (the circle is a special case). I wonder which/what sort of infinite series arise from/for the generalized elliptic scaling factors?
I rather suspect that the generalised elliptic scaling factor is a continuous function, so the answer may be a bit boring. For any infinite series with a finite sum I would be able to give you an ellipse (indeed, probably an infinite number of ellipses) whose scaling factor is a rational multiple of the sum.
For those unwilling to click-through, it essentially posits an alternate history where infinite series were explored by mathematicians before geometry, so rather than being surprised that the 'circle constant' is found in many infinite series, we would instead be surprised that the 'infinite series constant' is found in the geometry of a circle.