%I #7 Jan 20 2022 13:42:57
%S 0,1,0,2,1,0,3,2,1,0,4,3,2,1,0,5,4,3,2,1,0,6,5,4,3,2,1,0,7,6,5,4,3,2,
%T 1,0,8,7,6,5,4,3,2,1,0,9,8,7,6,5,4,3,2,1,0,10,9,8,7,6,5,4,3,2,1,0,11,
%U 10,9,8,7,6,5,4,3,2,1,0,12,11,10,9,8,7,6,5,4,3,2,1,0,13,12,11,10,9,8,7,6,5,4,3
%N Exponent of 9 (value of i) in n-th number of form 9^i*10^j.
%t Table[Range[n,0,-1],{n,0,15}]//Flatten (* _Harvey P. Dale_, Jan 20 2022 *)
%Y Differs from A025581 at a(253).
%K nonn
%O 1,4
%A _David W. Wilson_