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%I #22 Oct 14 2017 10:56:01
%S 166425621223026859056339052269787863565428,
%T 192910929628537040766341860254183960991698,
%U 307567270506730945853551459962385036145286,311906350108036145286307567270199935391877
%N Numbers n such that 11 iterations of 'Reverse and Subtract' lead to n, whereas fewer than 11 iterations do not lead to n.
%C There are 11 forty-two-digit terms in the sequence. Further terms are obtained (a) by inserting at the center of these terms either any number of 0's (for 166425621223026859056339052269787863565428, 311906350108036145286307567270199935391877, 466287189883036620417374974360601118217236, 658139747564935391877311906350534262959233, 703288139752915027377325180481642968027593) or any number of 9's (for the other six 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. - Clarified by _Ray Chandler_, Oct 14 2017.
%H Ray Chandler, <a href="/A292846/b292846.txt">Table of n, a(n) for n = 1..11</a>
%H J. H. E. Cohn, <a href="http://www.fq.math.ca/Scanned/28-2/cohn.pdf">Palindromic differences</a>, Fibonacci Quart. 28 (1990), no. 2, 113-120.
%F n = f^11(n), n <> f^k(n) for k < 11, where f: x -> |x - reverse(x)|.
%e 166425621223026859056339052269787863565428 -> 658139747564935391877311906350534262959233 -> 325180485129881782763533712811068515027377 -> 448540030730236434571833574377853069054146 -> 192910929628537040766341860254183960991698 -> 703288139752915027377325180481642968027593 -> 307567270506730945853551459962385036145286 -> 374974360076539008301807089075220036620417 -> 339052269946031972406296711860450026859056 -> 311906350108036145286307567270199935391877 -> 466287189883036620417374974360601118217236 -> 166425621223026859056339052269787863565428.
%Y Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292856, A292857, A292858, A292859.
%K nonn,base
%O 1,1
%A _Meritxell Vila Miñana_, Sep 24 2017
%E Terms corrected by _Ray Chandler_, Sep 27 2017