Grenz-Formel

An equation derived by Kronecker:

where  is the sum of squares function,  is the Riemann zeta function,  is the Dirichlet eta function,  is the gamma function, and the primed sum omits terms with zero denominator (Selberg and Chowla 1967).

REFERENCES:

Borwein, J. M. and Borwein, P. B. Pi & the AGM: A Study in Analytic Number Theory and Computational Complexity. New York: Wiley, pp. 296-297, 1987.

Selberg, A. and Chowla, S. "On Epstein's Zeta-Function." J. reine angew. Math. 227, 86-110, 1967.