Glaisher-Kinkelin Constant 

The Glaisher-Kinkelin constant  is defined by

(1)

(Glaisher 1878, 1894, Voros 1987), where  is the hyperfactorial, as well as

(2)

where  is the Barnes G-function.

It has closed-form representations

			(3)
			(4)
			(5)

(OEIS A074962) is called the Glaisher-Kinkelin constant and  is the derivative of the Riemann zeta function (Kinkelin 1860; Jeffrey 1862; Glaisher 1877, 1878, 1893, 1894; Voros 1987).

The constant  is implemented as Glaisher, and appears in a number of sums and integrals, especially those involving gamma functions and zeta functions.

Definite integrals include

			(6)
			(7)

(Glaisher 1878; Almqvist 1998; Finch 2003, p. 135), where  is the log gamma function.

Glaisher (1894) showed that

			(8)
			(9)
			(10)
			(11)

(OEIS A115521 and A115522; Glaisher 1894).

It also arises in the identity

			(12)
			(13)
			(14)
			(15)

(OEIS A073002; Glaisher 1894), which follows from the above products.

Guillera and Sondow (2005) give

(16)

Another more spectacular product is

			(17)
			(18)
			(19)

where  is the Dirichlet beta function and

			(20)
			(21)
			(22)

(Glaisher 1894).

It is also given by

(23)

where

			(24)
			(25)

(Glaisher 1878, 1894; who, however, failed to obtain the closed form of this expression).

REFERENCES:

Almkvist, G. "Asymptotic Formulas and Generalized Dedekind Sums." Experim. Math. 7, 343-356, 1998.

Finch, S. R. "Glaisher-Kinkelin Constant." §2.15 in Mathematical Constants. Cambridge, England: Cambridge University Press, pp. 135-145, 2003.

Glaisher, J. W. L. "On the Product ." Messenger Math. 7, 43-47, 1878.

Glaisher, J. W. L. "On Certain Numerical Products in which the Exponents Depend Upon the Numbers." Messenger Math. 23, 145-175, 1893.

Glaisher, J. W. L. "On the Constant which Occurs in the Formula for ." Messenger Math. 24, 1-16, 1894.

Guillera, J. and Sondow, J. "Double Integrals and Infinite Products for Some Classical Constants Via Analytic Continuations of Lerch's Transcendent." 16 June 2005 http://arxiv.org/abs/math.NT/0506319.

Havil, J. Gamma: Exploring Euler's Constant. Princeton, NJ: Princeton University Press, pp. 88 and 113, 2003.

Jeffrey, H. M. "On the Expansion of Powers of the Trigonometrical Ratios in Terms of Series of Ascending Powers of the Variables." Messenger Math. 5, 91-108, 1862.

Kinkelin. "Über eine mit der Gammafunktion verwandte Transcendente und deren Anwendung auf die Integralrechnung." J. reine angew. Math. 57, 122-158, 1860.

Sloane, N. J. A. Sequences A074962, A087501, A099791, A099792, A115521, and A115522 in "The On-Line Encyclopedia of Integer Sequences."

Voros, A. "Spectral Functions, Special Functions and the Selberg Zeta Function." Commun. Math. Phys. 110, 439-465, 1987.