OFFSET
1,2
COMMENTS
Inverse of A248618.
LINKS
Wikipedia, Gudermannian function.
FORMULA
Equals log(tan((2+Pi)/4)). - Vaclav Kotesovec, Oct 11 2014
From Amiram Eldar, Apr 07 2022: (Start)
Equals 2*arctanh(tan(1/2)).
Equals Integral_{x=0..1} sec(x) dx. (End)
EXAMPLE
1.22619117088351707081306096747190675272424835022074027913861684354298467624428...
MAPLE
evalf(log(tan((2+Pi)/4)), 100) # Vaclav Kotesovec, Oct 11 2014
MATHEMATICA
RealDigits[ InverseGudermannian[ 1], 10, 111][[1]]
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Robert G. Wilson v, Oct 09 2014
STATUS
approved