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A081480 Consider the mapping f(a/b) = (a^2 +b^2)/(a+b). Taking a =1, b = 2 to start with and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 1/2,5/3,17/4,305/21,... Sequence contains the denominators. 1
2, 3, 4, 21, 163, 23448, 1092023377, 596231923288918561, 355492505697703670063523236830811569, 126374921607231876111985200006557923908784362170241984606666354067170697 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The mapping f(a/b) = (a + b)/(a - b). Taking a = 2 b = 1 to start with and carrying out this mapping repeatedly on each new (reduced)rational number gives the periodic sequence 2/1,3/1,2/1,3/1,...

LINKS

Table of n, a(n) for n=1..10.

CROSSREFS

Cf. A081479.

Sequence in context: A183458 A109787 A109302 * A070841 A069801 A019074

Adjacent sequences:  A081477 A081478 A081479 * A081481 A081482 A081483

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Mar 24 2003

EXTENSIONS

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003

STATUS

approved

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Last modified June 20 23:34 EDT 2021. Contains 345313 sequences. (Running on oeis4.)