%I #15 Dec 14 2023 05:12:08
%S 19,28,37,46,55,64,73,82,91,19,28,37,46,55,64,73,82,91,19,28,37,46,55,
%T 64,73,82,91,19,28,37,46,55,64,73,82,91,19,28,37,46,55,64,73,82,91,19,
%U 28,37,46,55,64,73,82,91,19,28,37,46,55,64,73,82,91,19,28,37,46,55,64
%N Define the operations M: multiply by 11, D: divide by 11, R: reverse digits. Sequence gives trajectory of 19 under action of M,R,D,R.
%C Every such sequence is periodic. Sequences for a(1) = 1 to 18 are cyclic with a period of 1.
%e 19 > 209 > 902 > 82 > 28.
%t mrdr[n_]:=FromDigits[Reverse[IntegerDigits[FromDigits[ Reverse[ IntegerDigits[ 11n]]]/ 11]]]; NestList[mrdr,19,70] (* _Harvey P. Dale_, Oct 01 2015 *)
%K base,easy,nonn
%O 0,1
%A _Amarnath Murthy_, May 27 2003
%E Edited by _Patrick De Geest_ and _N. J. A. Sloane_, Jun 03 2003
