%I #9 Jul 16 2015 23:38:23
%S 1,10,11,18,19,56,136
%N Conway's subprime Fibonacci sequence: cycle lengths.
%C Similar to the Fibonacci recursion starting with a pair of positive integers, but each new nonprime term is divided by its least prime factor. The recursion enters a loop of length a(n) after a finite number of steps. Conjecture: the list of loops is complete (checked to [10^5, 10^5]), loops of length a(n) are unique and no infinite chains exist.
%H Richard K. Guy, Tanya Khovanova and Julian Salazar, <a href="http://arxiv.org/abs/1207.5099">Conway's subprime Fibonacci sequences</a>, arXiv:1207.5099v1 [math.NT]
%t see A214674
%Y Cf. A000045, A020639, A175723, A214551, A014682, A214674, A214892-A214898.
%K nonn
%O 1,2
%A _Wouter Meeussen_, Jul 29 2012