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, 9, 427, 39001680, 59326666963451131888009, 104404652929682490885549887204525469920253354571296599271372511202005

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