A292846 Numbers k such that 11 iterations of 'Reverse and Subtract' lead to k, whereas fewer than 11 iterations do not lead to k.

166425621223026859056339052269787863565428, 192910929628537040766341860254183960991698, 307567270506730945853551459962385036145286, 311906350108036145286307567270199935391877

Offset: 1

Author

Meritxell Vila Miñana, Sep 24 2017

Keywords

• nonn
• base

Comments

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.

Examples

			166425621223026859056339052269787863565428 -> 658139747564935391877311906350534262959233 -> 325180485129881782763533712811068515027377 -> 448540030730236434571833574377853069054146 -> 192910929628537040766341860254183960991698 -> 703288139752915027377325180481642968027593 -> 307567270506730945853551459962385036145286 -> 374974360076539008301807089075220036620417 -> 339052269946031972406296711860450026859056 -> 311906350108036145286307567270199935391877 -> 466287189883036620417374974360601118217236 -> 166425621223026859056339052269787863565428.
		

Links

• Ray Chandler, Table of n, a(n) for n = 1..11
• J. H. E. Cohn, Palindromic differences, Fibonacci Quart. 28 (1990), no. 2, 113-120.

Crossrefs

Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292856, A292857, A292858, A292859.

Formula

n = f^11(n), n <> f^k(n) for k < 11, where f: x -> |x - reverse(x)|.

Extensions

Terms corrected by Ray Chandler, Sep 27 2017