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A138371 Positions of digits after decimal point of tribonacii constant A058265 (root of polynomial x^3-x^2-x-1) where the approximation to this number by rational fraction does not improve the accuracy. +0
4
4, 5, 6, 7, 9, 12, 15, 17, 19, 21, 24, 25, 27, 28, 34, 38, 39, 41, 49, 50, 51, 56, 58, 64, 68, 69, 71, 72, 76, 77, 81, 85, 86, 88, 91, 95, 98, 100, 102, 104, 105, 107, 109, 111, 112, 113, 115, 117, 124, 126, 129, 133, 135, 136, 139, 142, 145, 148, 149, 151, 153, 160 (list; graph; listen)
OFFSET

1,1

COMMENT

Some numbers are giving empty set in this procedure. These numbers are e.g. Golden Ratio=(1+Sqrt[5])/2, Sqrt[2] what mean that if you need improove accuracy one decimal digit we have to uses new fraction with bigger integers as numerator and denominator. For all numbers sequence is that same also for 1/number.

EXAMPLE

a(1)=4 because 103/56 approximate Tribonacii constant to 3 and also 4 digits

MATHEMATICA

<< NumberTheory`Recognize` b = {}; a = {}; Do[k = Recognize[N[Root[ -1 - #1 - #1^2 + #1^3 &, 1], n + 1], 1, x]; If[MemberQ[a, k], AppendTo[b, n], AppendTo[a, k]], {n, 1, 500}]; b (*Artur Jasinski*)

CROSSREFS

Cf. A138335, A138336, A138337, A138338, A138339, A138343, A138366, A138367, A138369, A138370.

Adjacent sequences: A138368 A138369 A138370 this_sequence A138372 A138373 A138374

Sequence in context: A010399 A008523 A047568 this_sequence A139453 A010391 A010419

KEYWORD

base,nonn,uned,probation

AUTHOR

Artur Jasinski (grafix(AT)csl.pl), Mar 17 2008

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Last modified January 8 02:43 EST 2009. Contains 152824 sequences.


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