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%I #17 Apr 07 2022 09:21:00
%S 1,2,2,6,1,9,1,1,7,0,8,8,3,5,1,7,0,7,0,8,1,3,0,6,0,9,6,7,4,7,1,9,0,6,
%T 7,5,2,7,2,4,2,4,8,3,5,0,2,2,0,7,4,0,2,7,9,1,3,8,6,1,6,8,4,3,5,4,2,9,
%U 8,4,6,7,6,2,4,4,2,8,0,3,8,1,6,9,2,3,7,4,2,5,6,3,7,7,9,6,6,0,9,5,3,3,4,6,9
%N Decimal expansion of the solution when Gudermannian(x) equals 1.
%C Inverse of A248618.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Gudermannian_function">Gudermannian function</a>.
%F Equals log(tan((2+Pi)/4)). - _Vaclav Kotesovec_, Oct 11 2014
%F From _Amiram Eldar_, Apr 07 2022: (Start)
%F Equals 2*arctanh(tan(1/2)).
%F Equals Integral_{x=0..1} sec(x) dx. (End)
%e 1.22619117088351707081306096747190675272424835022074027913861684354298467624428...
%p evalf(log(tan((2+Pi)/4)),100) # _Vaclav Kotesovec_, Oct 11 2014
%t RealDigits[ InverseGudermannian[ 1], 10, 111][[1]]
%Y Cf. A248618.
%K nonn,cons
%O 1,2
%A _Robert G. Wilson v_, Oct 09 2014