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A212480
Decimal expansion of the argument of infinite power tower of i.
1
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, 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, 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
OFFSET
0,1
COMMENTS
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).
LINKS
Eric Weisstein's World of Mathematics, Power Tower
FORMULA
c = arg(i^i^i^...).
EXAMPLE
0.6884532271077021304987675711768242596 ...
MATHEMATICA
2*I*ProductLog[-I*Pi/2]/Pi // Arg // N[#, 108]& // RealDigits[#][[1]]& (* Jean-François Alcover, Feb 05 2013 *)
PROG
(PARI) \\ start with I^(0.4+0.4*I) and iterate (%+I^%)/2. It converges pretty rapidly to z.
CROSSREFS
Cf. A077589 (real part of z), A077590 (imaginary part of z), A212479 (absolute value of z).
Sequence in context: A375067 A176104 A011481 * A100221 A157683 A300897
KEYWORD
nonn,cons,easy
AUTHOR
Stanislav Sykora, May 17 2012
STATUS
approved