%I #3 Dec 05 2013 19:56:01

%S 2,3,4,21,163,23448,1092023377,596231923288918561,

%T 355492505697703670063523236830811569,

%U 126374921607231876111985200006557923908784362170241984606666354067170697

%N 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.

%C 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,...

%Y Cf. A081479.

%K nonn

%O 1,1

%A _Amarnath Murthy_, Mar 24 2003

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