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%I #6 Sep 27 2017 11:47:14
%S 11436678,13973058,19582398,23981958,30581397,32662377,33218856,
%T 42464466,44664246,48737106,61936974,69746193,71064873,76226733
%N Numbers n such that 14 applications of 'Reverse and Subtract' lead to n, whereas fewer than 14 applications do not lead to n.
%C There are 14 eight-digit terms in the sequence. Further terms are obtained (a) by inserting at the center of these terms either any number of 9's (for 11436678, 32662377, 33218856, 76226733) or any number of 0's (for the other ten terms) and (b) by concatenating a term any number of times with itself and inserting an equal number of 0's at all junctures. Method (b) may be applied recursively to all terms. - Revised thanks to a comment from Hans Havermann, Jan 20 2004.
%F n = f^14(n), n <> f^k(n) for k < 14, where f: x -> |x - reverse(x)|.
%e 11436678 -> 76226733 -> 42464466 -> 23981958 -> 61936974 -> 13973058 -> 71064873 -> 33218856 -> 32662377 -> 44664246 -> 19582398 -> 69746193 -> 30581397 -> 48737106 -> 11436678.
%Y Cf. A072137, A072140, A072141, A072143, A072718, A072719.
%K base,nonn
%O 1,1
%A _Klaus Brockhaus_, Jun 24 2002