%I #27 May 22 2023 02:45:12
%S 3,6,8,9,10,13,21,23,27,28,29,31,32,35,36,37,39,40,41,42,43,46,47,52,
%T 57,58,61,62,65,67,69,70,72,76,80,81,82,83,85,86,88,89,91,92,94,96,97,
%U 98,102,103,105,107,111,112
%N Positions of ones in binary expansion of arctan(1/2)/Pi.
%D Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 430-433.
%H T. D. Noe, <a href="/A004715/b004715.txt">Table of n, a(n) for n=1..1000</a>
%H J. M. Borwein and R. Girgensohn, <a href="http://dx.doi.org/10.4153/CJM-1995-013-4">Addition theorems and binary expansions</a>, Canadian J. Math. 47 (1995) 262-273.
%H Steven R. Finch, <a href="http://www.people.fas.harvard.edu/~sfinch/constant/plff/plff.html">Plouffe's Constant</a>. [Broken link]
%H Steven R. Finch, <a href="http://web.archive.org/web/20010624104257/http://www.mathsoft.com/asolve/constant/plff/plff.html">Plouffe's Constant</a>. [From the Wayback machine]
%H Simon Plouffe, <a href="https://cs.uwaterloo.ca/journals/JIS/compass.html">The Computation of Certain Numbers Using a Ruler and Compass</a>, J. Integer Seq., Vol. 1 (1998), Article 98.1.3.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PlouffesConstant.html">Plouffe's Constant</a>.
%t Position[Join[{0, 0}, RealDigits[ArcTan[1/2]/Pi, 2, 120][[1]]], 1] // Flatten (* _Amiram Eldar_, May 22 2023 *)
%Y Cf. A028999.
%K nonn,base
%O 1,1
%A _Simon Plouffe_