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%I #25 Oct 02 2022 00:13:19
%S 9,7,0,8,0,5,5,1,9,3,6,2,7,3,3,2,8,8,6,7,3,4,3,2,8,1,4,9,8,1,3,4,7,9,
%T 7,8,8,1,7,3,3,4,9,4,6,9,2,3,0,2,4,1,4,9,7,5,3,6,9,4,1,0,8,4,7,1,0,8,
%U 1,3,6,8,5,8,3,2,4,4,8,0,1,6,1,9,0,2,6,8,9,7,5,0,5,9,1,2,5,4,3,0,5,8,2,3
%N Decimal expansion of Pi/(2*phi).
%C This is the middle angle (in radians) of the unique right triangle whose angles are in geometric progression; common ratio is phi and the angles are (Pi/(2*phi^2), Pi/(2*phi), Pi/2) in radians, corresponding to approximately (34.377, 55.623, 90) in degrees.
%H <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%F Equals A019669/A001622 = A094881/2 = Pi/(1+sqrt(5)) = (Pi/4) * (sqrt(5)-1).
%e 0.970805519362733288673432814981347978817334946923024149753694108...
%p evalf(Pi/(1+sqrt(5)),150);
%t RealDigits[Pi/(2*GoldenRatio), 10, 100][[1]] (* _Amiram Eldar_, Feb 09 2021 *)
%o (PARI) Pi/(1+sqrt(5)) \\ _Michel Marcus_, Feb 09 2021
%Y Cf. A000796 (Pi), A001622 (phi), A019669 (Pi/2), A180014 (Pi/(2*phi^2)).
%K nonn,cons
%O 0,1
%A _Bernard Schott_, Feb 09 2021
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