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Decimal expansion of the probability that a random real number is evil.
4

%I #16 Jan 18 2024 08:03:04

%S 1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,

%T 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,7,8,3,3,7,

%U 7,7,3,1,6,2,8,6,4,7,6,0,5,5,2,7,9,4,6,2,5,9,4,0,6,5,1,3,3,3,2,7,7,5,6,1,9

%N Decimal expansion of the probability that a random real number is evil.

%C A real number is said to be evil if the cumulative sum of its digits following the decimal point 'hits' the value 666. It is amazing how close this value is to 1/5 (the difference is in A271881).

%H Stanislav Sykora, <a href="/A271880/b271880.txt">Table of n, a(n) for n = 0..2000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/EvilNumber.html">Evil Number</a>.

%F Equals A100061(666)/A100062(666).

%e 0.19999999999999999999999999999999999999999999999999999999999999978337...

%t RealDigits[SeriesCoefficient[(1 - x^9)/(x^10 - 10 x + 9), {x, 0, 665}], 10, 120][[1]] (* _Amiram Eldar_, May 24 2023 *)

%o (PARI) 0.0 + Vec(Ser((1-x^9)/(x^10-10*x+9),x,666))[666]

%Y Cf. A001019, A010734, A100061, A100062, A271881.

%K nonn,cons,base

%O 0,2

%A _Stanislav Sykora_, Apr 16 2016