%I #20 Jan 12 2017 04:40:30
%S 3,9,3,9,1,2,7,7,5,5,0,0,8,0,4,5,3,5,7,0,2,8,2,1,6,2,5,4,6,6,3,7,5,1,
%T 3,4,1,3,0,7,1,7,8,1,4,0,7,3,1,7,3,7,2,3,5,5,1,6,8,0,0,4,9,8,9,7,9,9,
%U 3,2,6,6,8,7,2,3,1,3,1,9,4,9,1,6,4,5,5,5,0,8,9,8,0,1,6,1,6,7,4,7,9,7,4,5,9,0,7,6,0,4,7,2,5,8,7,7,2,4,0,3
%N Decimal expansion of sqrt(Pi + Pi*sqrt(Pi + Pi*sqrt(Pi + ...))).
%H G. C. Greubel, <a href="/A268580/b268580.txt">Table of n, a(n) for n = 1..5000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Pi.html">Pi</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/NestedRadical.html">Nested Radical</a>
%F Equals (Pi + sqrt(Pi^2 + 4*Pi))/2.
%e 3.9391277550080453570282162546637513413...
%t RealDigits[(Pi + Sqrt[Pi^2 + 4 Pi])/2, 10, 120][[1]]
%o (PARI) (Pi + sqrt(Pi^2 + 4*Pi))/2 \\ _Michel Marcus_, Feb 21 2016
%Y Cf. A000796, A100941, A189970.
%K nonn,cons
%O 1,1
%A _Ilya Gutkovskiy_, Feb 21 2016