This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A222135 #12 Jul 02 2025 11:01:34 %S A222135 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 A222135 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 A222135 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 A222135 Decimal expansion of sqrt(5 - sqrt(5 - sqrt(5 - sqrt(5 - ... )))). %C A222135 Sequence with a(1) = 2 is decimal expansion of sqrt(5 + sqrt(5 + sqrt(5 + sqrt(5 + ... )))) - A222134. %F A222135 Closed form: (sqrt(21) - 1)/2 = A090458-2 = A107905-3 = A222134-1. %F A222135 sqrt(5 - sqrt(5 - sqrt(5 - sqrt(5 - ... )))) + 1 = sqrt(5 + sqrt(5 + sqrt(5 + sqrt(5 + ... )))). See A222134. %F A222135 Minimal polynomial: x^2 + x - 5. - _Stefano Spezia_, Jul 02 2025 %e A222135 1.791287847477920003294023596864... %t A222135 RealDigits[(Sqrt[21] - 1)/2, 10, 130] %Y A222135 Cf. A090458, A107905, A222134. %K A222135 nonn,cons,easy %O A222135 1,2 %A A222135 _Jaroslav Krizek_, Feb 08 2013