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Decimal expansion of 1/sqrt(27).
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%I #46 Dec 24 2024 13:45:49

%S 1,9,2,4,5,0,0,8,9,7,2,9,8,7,5,2,5,4,8,3,6,3,8,2,9,2,6,8,3,3,9,8,5,8,

%T 1,8,5,4,9,2,0,0,5,8,3,7,5,6,7,0,8,9,5,8,6,7,2,8,6,7,4,4,2,1,6,1,3,2,

%U 5,8,9,0,7,6,7,6,4,4,4,4,8,5,6,4,5,7,1,7,9,8,5,2,8,5,8,3,1,7,5

%N Decimal expansion of 1/sqrt(27).

%C This is the minimum ripple factor for a third-order Chebyshev filter for which the generalized reflectionless topology needs no negative elements. - _Matthew A. Morgan_, Oct 18 2017

%D Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Sections 8.4.3 and 8.16, pp. 495, 527.

%H Ivan Panchenko, <a href="/A020784/b020784.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>.

%F Equals Sum_{k>=0} binomial(2*k,k) * k/16^k. - _Amiram Eldar_, Aug 02 2020

%F Equals sqrt(3)/9. - _Stefano Spezia_, Dec 24 2024

%F Equals 1/A010482 = A020760/3 = sqrt(A021031) = A073010/Pi = A212886/2. - _Hugo Pfoertner_, Dec 24 2024

%e 0.1924500897298752548363829268339858185492005837567089586728674....

%t RealDigits[1/Sqrt[27],10,200][[1]] (* _Vladimir Joseph Stephan Orlovsky_, May 30 2010 *)

%o (PARI) 1/sqrt(27) \\ _G. C. Greubel_, Feb 15 2018

%o (Magma) 1/Sqrt(27); // _G. C. Greubel_, Feb 15 2018

%Y Cf. A002194, A010482, A020760, A021031, A073010, A212886.

%K nonn,cons,easy

%O 0,2

%A _N. J. A. Sloane_