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%I #18 Jul 01 2024 19:21:39
%S 9,1,7,1,5,2,3,3,5,6,6,7,2,7,4,3,4,6,3,7,3,0,9,2,9,2,1,4,4,2,6,1,8,7,
%T 7,5,3,6,7,9,2,7,1,4,8,6,0,1,0,8,8,9,4,5,3,4,3,5,7,4,1,2,4,2,9,1,5,0,
%U 6,1,7,1,4,0,7,0,1,9,7,1,5,0,4,4,1,4,9,4,8,6,4,6
%N Decimal expansion of tanh(Pi/2).
%D Calvin C. Clawson, Mathematical Mysteries: The Beauty and Magic of Numbers, Springer, 2013. See p. 225.
%F Equals 1/A367961 = A367959 / A308715 = (2/Pi)*A228048.
%F Equals (e^Pi - 1)/(e^Pi + 1) = K_{n>0} Pi^(2-[n=1])/(4*n - 2) (see Clawson at p. 225). - _Stefano Spezia_, Jul 01 2024
%e 0.91715233566727434637309...
%p evalf(tanh(Pi/2)) ;
%t First[RealDigits[Tanh[Pi/2],10,100]] (* _Paolo Xausa_, Dec 06 2023 *)
%Y Cf. A367961, A367959, A308715, A083124 (cont. frac).
%K nonn,cons
%O 0,1
%A _R. J. Mathar_, Dec 06 2023