

A270316


Denominators of rEgyptian fraction expansion for (1/2)^(1/3), where r = (1,1/2,1/3,1/4,...)


2



2, 2, 8, 123, 149367, 19877572990, 3398650153657920854371, 38501744904404393452660892011327652171148221, 1751742507912624184333715455628345093210972368514121272905550101268413741408122585972087
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OFFSET

1,1


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(k1)), and f(k) = f(k1)  r(k)/n(k). Then x = r(1)/n(1) + r(2)/n(2) + r(3)/n(3) + ... , the rEgyptian 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

(1/2)^(1/3) = 1/2 + 1/(2*2) + 1/(3*8) + ...


MATHEMATICA

r[k_] := 1/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 = (1/2)^(1/3); Table[n[x, k], {k, 1, z}]


CROSSREFS

Cf. A269993.
Sequence in context: A270555 A270405 A047692 * A069561 A180370 A326939
Adjacent sequences: A270313 A270314 A270315 * A270317 A270318 A270319


KEYWORD

nonn,frac,easy


AUTHOR

Clark Kimberling, Mar 17 2016


STATUS

approved



