A292858 Numbers k such that 9 applications of 'Reverse and Subtract' lead to k, whereas fewer than 9 applications do not lead to k.

111603518721165960373027269626940447783074704878, 176512193475025275151977319848516480415708873428, 230594281653466673786238177213613424643828503868, 305623327188018690392981819607012089228265673497

Offset: 1

Author

Meritxell Vila Miñana, Sep 25 2017

Keywords

• nonn
• base

Comments

There are 9 forty-eight-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 111603518721165960373027269626940447783074704878, 176512193475025275151977319848516480415708873428, 637711546692957642526533655473763239712353991164, 647866614039059340696936459303056040158682342243, 766803951666578089253935450746129113344740601233) or any number of 9's (for the other four 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

			111603518721165960373027269626940447783074704878 -> 766803951666578089253935450746129113344740601233 -> 434697904223266167606880911393148237678581292566 -> 230594281653466673786238177213613424643828503868 -> 637711546692957642526533655473763239712353991164 -> 176512193475025275151977319848516480415708873428 -> 647866614039059340696936459303056040158682342243 -> 305623327188018690392981819607012089228265673497 -> 488753235634961520313936369686084721653457653006 -> 111603518721165960373027269626940447783074704878
		

Links

• Ray Chandler, Table of n, a(n) for n = 1..9
• J. H. E. Cohn, Palindromic differences, Fibonacci Quart. 28 (1990), no. 2, 113-120.

Crossrefs

Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292846, A292856, A292857, A292859.

Formula

n = f^9(n), n <> f^k(n) for k < 9, where f: x -> |x - reverse(x)|.

Extensions

Terms ordered by Ray Chandler, Sep 27 2017