This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A292858 #18 Jun 27 2025 17:53:18 %S A292858 111603518721165960373027269626940447783074704878, %T A292858 176512193475025275151977319848516480415708873428, %U A292858 230594281653466673786238177213613424643828503868,305623327188018690392981819607012089228265673497 %N A292858 Numbers k such that 9 applications of 'Reverse and Subtract' lead to k, whereas fewer than 9 applications do not lead to k. %C A292858 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. %H A292858 Ray Chandler, <a href="/A292858/b292858.txt">Table of n, a(n) for n = 1..9</a> %H A292858 J. H. E. Cohn, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/28-2/cohn.pdf">Palindromic differences</a>, Fibonacci Quart. 28 (1990), no. 2, 113-120. %F A292858 n = f^9(n), n <> f^k(n) for k < 9, where f: x -> |x - reverse(x)|. %e A292858 111603518721165960373027269626940447783074704878 -> 766803951666578089253935450746129113344740601233 -> 434697904223266167606880911393148237678581292566 -> 230594281653466673786238177213613424643828503868 -> 637711546692957642526533655473763239712353991164 -> 176512193475025275151977319848516480415708873428 -> 647866614039059340696936459303056040158682342243 -> 305623327188018690392981819607012089228265673497 -> 488753235634961520313936369686084721653457653006 -> 111603518721165960373027269626940447783074704878 %Y A292858 Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292846, A292856, A292857, A292859. %K A292858 nonn,base %O A292858 1,1 %A A292858 _Meritxell Vila Miñana_, Sep 25 2017 %E A292858 Terms ordered by _Ray Chandler_, Sep 27 2017