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 A212480 #16 Feb 16 2025 08:33:17 %S A212480 6,8,8,4,5,3,2,2,7,1,0,7,7,0,2,1,3,0,4,9,8,7,6,7,5,7,1,1,7,6,8,2,4,2, %T A212480 5,9,6,0,8,0,9,5,4,4,3,2,3,2,2,2,3,1,3,5,5,2,8,6,8,6,9,2,3,2,1,0,4,4, %U A212480 9,7,0,7,3,0,1,9,4,0,3,2,7,4,3,8,3,5,2,5,7,3,1,1,0,2,3,0,1,6,5,8,9,7,0,3,0,8,1,5 %N A212480 Decimal expansion of the argument of infinite power tower of i. %C A212480 This c, expressed in radians, equals arg(z), where z is the complex solution of z = i^z or, equivalently, z = i^i^i^... Also, c = atan(A077590/A077589). %H A212480 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PowerTower.html">Power Tower</a> %F A212480 c = arg(i^i^i^...). %e A212480 0.6884532271077021304987675711768242596 ... %t A212480 2*I*ProductLog[-I*Pi/2]/Pi // Arg // N[#, 108]& // RealDigits[#][[1]]& (* _Jean-François Alcover_, Feb 05 2013 *) %o A212480 (PARI) \\ start with I^(0.4+0.4*I) and iterate (%+I^%)/2. It converges pretty rapidly to z. %Y A212480 Cf. A077589 (real part of z), A077590 (imaginary part of z), A212479 (absolute value of z). %K A212480 nonn,cons,easy %O A212480 0,1 %A A212480 _Stanislav Sykora_, May 17 2012