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Decimal expansion of Product_{k>=1} (1 - exp(-Pi*k/4)).
10

%I #8 Dec 17 2023 09:42:45

%S 3,5,9,8,9,2,6,7,8,2,0,3,6,5,2,8,9,9,3,3,9,4,3,0,2,6,5,5,4,2,3,2,2,6,

%T 8,4,1,3,7,9,8,2,4,0,4,6,9,9,2,8,6,5,6,5,6,7,6,0,7,3,6,6,0,8,1,5,2,1,

%U 9,8,2,6,7,4,7,9,1,8,0,7,4,3,5,2,9,9,5,9,1,2,0,5,4,3,6,6,9,7,9,7,8,2,8,5,3,9

%N Decimal expansion of Product_{k>=1} (1 - exp(-Pi*k/4)).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/DedekindEtaFunction.html">Dedekind Eta Function</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/q-PochhammerSymbol.html">q-Pochhammer Symbol</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Dedekind_eta_function">Dedekind eta function</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Euler_function">Euler function</a>

%F Equals (6*sqrt(22*sqrt(2)-24) - 16)^(1/8) * exp(Pi/96)* Gamma(1/4) / (2*Pi^(3/4)).

%e 0.359892678203652899339430265542322684137982404699286565676073660815219...

%t RealDigits[(6*Sqrt[22*Sqrt[2] - 24] - 16)^(1/8) * E^(Pi/96) * Gamma[1/4] / (2*Pi^(3/4)), 10, 120][[1]]

%t RealDigits[QPochhammer[E^(-Pi/4)], 10, 120][[1]]

%Y Cf. A259147, A259148, A259149, A259150, A259151, A292862, A292864, A368211.

%K nonn,cons

%O 0,1

%A _Vaclav Kotesovec_, Sep 25 2017