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A128385 a(n) = denominator of r(n): r(n) is such that the continued fraction (of rational terms) [r(1);r(2),...,r(n)] = b(n) for every positive integer n, where b(1) = 1 and b(n+1) = 1 + 1/b(n)^2 for.every positive integer n. +0
2
1, 1, 3, 13, 289 (list; graph; listen)
OFFSET

1,3

COMMENT

b(n) = A076725(n)/A076725(n-1)^2. The limit, as n -> infinity, of r(n)*r(n+1) = (2 /x^3) + (x^3 /2) - 2, where x is the real root of x^3 -x^2 -1 = 0. (This limit result needs some checking.)

LINKS

Leroy Quet, Home Page (listed in lieu of email address)

EXAMPLE

{r(n)}: 1, 1, 1/3, 9/13, 91/289,...

b(4) = 41/25 = 1 + 1/(1 + 1/(1/3 + 13/9)).

And b(5) = 2306/1681 = 1 + 1/(1 + 1/(1/3 + 1/(9/13 + 289/91))).

CROSSREFS

Cf. A128384, A076725.

Sequence in context: A006487 A042823 A132560 this_sequence A100524 A000859 A045748

Adjacent sequences: A128382 A128383 A128384 this_sequence A128386 A128387 A128388

KEYWORD

frac,more,nonn

AUTHOR

Leroy Quet Feb 28 2007

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Last modified November 27 14:50 EST 2009. Contains 167570 sequences.


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