March 14th

When Professor Ricardo Estrada worked with Jasson Vindas (Ghent University, Belgium; LSU Math PhD 2009) on the preparation of their paper Exterior Euler Summability, J. Math. Anal. Appl. 388 (2012), pp. 48-60, they realized that their results could be applied to recover the following formula for pi:

Estrada Pi 

This relates pi to the Riemann zeta function:

Riemann zeta 

The formula for pi was first discovered by Flajolet and Vardi in an unpublished manuscript from 1996.