%I #8 Feb 11 2013 11:55:40
%S 1,7,9,1,2,8,7,8,4,7,4,7,7,9,2,0,0,0,3,2,9,4,0,2,3,5,9,6,8,6,4,0,0,4,
%T 2,4,4,4,9,2,2,2,8,2,8,8,3,8,3,9,8,5,9,5,1,3,0,3,6,2,1,0,6,1,9,5,3,4,
%U 3,4,2,1,2,7,7,3,8,8,5,4,4,3,3,0,2,1,8,0,7,7,9,7,4,6,7,2,2,5,1,6,3
%N Decimal expansion of sqrt(5 - sqrt(5 - sqrt(5 - sqrt(5 - ... )))).
%C Sequence with a(1) = 2 is decimal expansion of sqrt(5 + sqrt(5 + sqrt(5 + sqrt(5 + ... )))) - A222134.
%F Closed form: (sqrt(21) - 1)/2 = A090458-2 = A107905-3 = A222134-1.
%F sqrt(5 - sqrt(5 - sqrt(5 - sqrt(5 - ... )))) + 1 = sqrt(5 + sqrt(5 + sqrt(5 + sqrt(5 + ... )))). See A222134.
%e 1.791287847477920003294023596864...
%t RealDigits[(Sqrt[21] - 1)/2, 10, 130]
%Y Cf. A090458, A107905, A222134.
%K nonn,cons
%O 1,2
%A _Jaroslav Krizek_, Feb 08 2013
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