A081482 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 denominators.

2, 5, 53, 92569, 1521139611842161, 1759826706496123129893760473796973076447567001, 5450165776683729363553774731808009059782198745252457060273092560160498157854877231868041524958184901475157837190479609639387791150077013

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..7.

Crossrefs

Cf. A081481.

Sequence in context: A071880 A071882 A206848 * A134475 A218030 A114029

Adjacent sequences: A081479 A081480 A081481 * A081483 A081484 A081485

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