ArcSinh[z] == (z Sqrt[1 + z^2])/ (1 + (1 2 z^2)/(3 + (1 2 z^2)/(5 + (3 4 z^2)/ (7 + (3 4 z^2)/(9 + (5 6 z^2)/(11 + \[Ellipsis])))))) /; !IntervalMemberQ[Interval[{-Infinity, -1}], I z] && !IntervalMemberQ[Interval[{1, Infinity}], I z]

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2001-10-29