login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A081481 Consider the mapping f(a/b) = (a^3 +b^3)/(a^2+b^2). Taking a =1, b = 2 to start with and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 1/2,9/5,427/53,39001680/92569,... Sequence contains the numerator. 1
1, 9, 427, 39001680, 59326666963451131888009, 104404652929682490885549887204525469920253354571296599271372511202005 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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..6.

CROSSREFS

Cf. A081482.

Sequence in context: A292073 A232249 A229843 * A160376 A271652 A156092

Adjacent sequences:  A081478 A081479 A081480 * A081482 A081483 A081484

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 20 23:24 EDT 2021. Contains 345312 sequences. (Running on oeis4.)