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let $\epsilon >0$, I tried to evaluate $\int_{0+\epsilon}^{1-\epsilon}\left(\sqrt{1-x^2}^{\sqrt{1-x^2}^{\cdots}}\right) dx$ , using the fact $x= \cos t$ yield to have integrand using $\sin $ function seems is not easy to get such closed form by this variable change , For one iteration by means $\int_{0}^{1}\left(\sqrt{1-x^2}^{\sqrt{1-x^2}}\right) dx$ we have the integrand converge approximately to $\frac{\sqrt{3}}{{2}}$, For some odd iterations we have $l=0.89..$ and for even iterations we have $l=0.9..$ , Now if we fixe $\epsilon$ at at some small value for example $\epsilon=0.05$ such that $x$ lie at a least between $(0+\epsilon,0.99782-\epsilon)$ to get convergence , My question here is : Is it possible to express the titled integral in elementary functions ?

Note:The Copy of this question is posted yesterday here in MSE, And I bielive that integrand has a closed form because the integrand is of the trigonometric form

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  • $\begingroup$ I guess $l$ is the first integral with an infinite sequence of powers. $\endgroup$ Commented Jul 15, 2020 at 13:51
  • $\begingroup$ Note: the continued exponential $u^{u^{\dots}}$ does not converge for $u$ near $0$. In your case, the integrand does not converge for $x$ near $1$. $\endgroup$ Commented Jul 15, 2020 at 14:23
  • $\begingroup$ @GeraldEdgar , I have edited it to assure convergence look it and thanks $\endgroup$ Commented Jul 15, 2020 at 15:34

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I think this is $$ -\int_{0+\epsilon}^{1-\epsilon} {\frac {2\;{\rm W} \left(-\frac12\,\ln \left( 1-{x }^{2} \right) \right)}{\ln \left( 1-{x}^{2} \right) }}\,{\rm d}x $$ not elementary.

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  • $\begingroup$ Could u explain a little bit how you got this form ? $\endgroup$ Commented Jul 15, 2020 at 22:40

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