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%I #4 Jul 11 2015 00:36:26
%S 0,1,10,16,14,15,13,1011,1017,1037,1027,1014,1013,1028,100113,100104,
%T 100145,100134,100103,100112,100133,100187,100114,100128,100194,
%U 100107,100307,100277,100413,100345,100429,100215,100427,100214,100433,100335
%N Smallest k whose 'Reverse and Subtract' trajectory has a preperiodic part of length n.
%C 'Reverse and Subtract' (cf. A072137) is defined by x -> |x - reverse(x)|. For small n the last term of the preperiodic part of the trajectory (cf. A072139) is a palindrome, so this sequence is a weak analog of A033665, which uses 'Reverse and Add'. - 1012 is the first n such that last term of the preperiodic part is not palindromic (cf. A072140).
%e a(8) = 1017, since 1017 is the smallest number whose 'Reverse and Subtract' trajectory has eight preperiodic terms: 1017 -> 6084 -> 1278 -> 7443 -> 3996 -> 2997 -> 4995 -> 999.
%Y Cf. A033665, A072137, A072139, A072140, A072146.
%K base,nonn
%O 0,3
%A _Klaus Brockhaus_, Jun 24 2002
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