%I #6 Mar 30 2012 18:39:12
%S 0,0,1,0,2,2,3,0,4,4,5,4,6,6,7,4,8,8,9,8,10,10,11,10,12,12,13,9,14,14,
%T 15,14,1,6,16,17,16,18,18,19,17,20,20,21,19,22,22,23,21,24,24,25,23,
%U 26,26,27,26,28,28,29,27,30,30,31,30,32,32,33,31,34,34,35,34,36,36,37,35
%N Let u(1)=u(2)=1, u(n)=abs(u(n-1)-3/2*u(n-2)); then a(n) is the exponent of 2 in denominator of u(n).
%C Does u(n) diverge to infinity?
%F a(n)<n/2, a(2n+1)=n+1.
%o (PARI) a=b=1; for(n=3,100,c=abs(b-3*a/2); a=b; b=c; print1(valuation(denominator(c),2), ","))
%K nonn
%O 1,5
%A _Benoit Cloitre_, Jan 30 2003