OFFSET
1,1
REFERENCES
Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.7 Lengyel's constant, p. 318.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..2500
EXAMPLE
7.37194949076622733754141...
MATHEMATICA
digits = 100; EllipticTheta[2, 0, 1/2]/NProduct[1 - 2^(-j), {j, 1, Infinity}, WorkingPrecision -> digits + 10, NProductFactors -> digits] // RealDigits[#, 10, digits]& // First
RealDigits[EllipticTheta[2, 0, 1/2]/QPochhammer[1/2, 1/2], 10, 100][[1]] (* Vladimir Reshetnikov, Oct 17 2016 *)
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Jean-François Alcover, May 27 2014
STATUS
approved