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A270477 Denominators of r-Egyptian fraction expansion for sqrt(1/3), where r(k) = 1/Prime(k). 1
1, 5, 19, 909, 709338, 4794024440479, 18787437394610419733587349, 438597049892989902759955952867127541411726874886473, 175915259950103387380668466916070098283235189077796884344520632101017268238077131833609385455236441012 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Suppose that r is a sequence of rational numbers r(k) <= 1 for k >= 1, and that x is an irrational number in (0,1).  Let f(0) = x, n(k) = floor(r(k)/f(k-1)), and f(k) = f(k-1) - r(k)/n(k).  Then x = r(1)/n(1) + r(2)/n(2) + r(3)/n(3) + ... , the r-Egyptian fraction for x.

See A269993 for a guide to related sequences.

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..11

Eric Weisstein's World of Mathematics, Egyptian Fraction

Index entries for sequences related to Egyptian fractions

EXAMPLE

sqrt(1/3) = 1/(2*1) + 1/(3*5) + 1/(5*19) + 1/(7*909) + ...

MATHEMATICA

r[k_] := 1/Prime[k]; f[x_, 0] = x; z = 10;

n[x_, k_] := n[x, k] = Ceiling[r[k]/f[x, k - 1]]

f[x_, k_] := f[x, k] = f[x, k - 1] - r[k]/n[x, k]

x = Sqrt[1/3]; Table[n[x, k], {k, 1, z}]

CROSSREFS

Cf. A269993, A000040.

Sequence in context: A072526 A095218 A119964 * A279256 A174490 A280034

Adjacent sequences:  A270474 A270475 A270476 * A270478 A270479 A270480

KEYWORD

nonn,frac,easy

AUTHOR

Clark Kimberling, Mar 30 2016

STATUS

approved

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Last modified September 22 16:49 EDT 2020. Contains 337291 sequences. (Running on oeis4.)