%I
%S 1,0,3,5,4,0,5,10,7,11,6,0,7,16,11,9,10,21,8,0,9,21,12,27,11,14,17,23,
%T 10,0,11,32,18,27,18,13,15,28,19,32,12,0,13,38,25,19,18,47,15,44,16,
%U 38,18,50,14,0,15,39,20,59,18,54,28,17,24,31,21,28,29,49,16,0,17
%N Length of cycle produced by the function f: (x; y; z) >(xyz; y; 2*y + z) if y + = z <x and (x; y; z) >(y + z x; x; 2*x z) if y +z >x when started at (n,1,1).
%F a(k^2 + k) = 0, a(k^2 + k  1) = 2*k, a(k^2 + k + 1) = a(k^2) = 2*k + 1
%e a(5) = 4 because (5; 1; 1) > (3; 1; 3) > (1; 3; 3) > (5; 1; = 1) > (5; 1; 1) : length of cycle =4.
%Y Cf. A087855.
%K nonn
%O 1,3
%A _Philippe Deléham_, Sep 24 2003
