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 A292857 #21 Jun 27 2025 18:29:18 %S A292857 16914079504181797053273763831171860502859028, %T A292857 16914099886383117186009041817970531210859028, %U A292857 31253512653248719266062943707325665377464777,31253591994370732566027032487192660079464777 %N A292857 Numbers k such that 8 applications of 'Reverse and Subtract' lead to k, whereas fewer than 8 applications do not lead to k. %C A292857 There are 8 forty-four-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 16914079504181797053273763831171860502859028, 46492964703403651468863122584458570244070436, 65181741002635316783463471248546280094182933) or any number of 9's (for the other five 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 A292857 Ray Chandler, <a href="/A292857/b292857.txt">Table of n, a(n) for n = 1..8</a> %H A292857 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 A292857 n = f^8(n), n <> f^k(n) for k < 8, where f: x -> |x - reverse(x)|. %e A292857 16914079504181797053273763831171860502859028 -> 65181741002635316783463471248546280094182933 -> 31253591994370732566027032487192660079464777 -> 46492905012258445857045034036514689840070436 -> 16914099886383117186009041817970531210859028 -> 65181701327124854628081026353167837688182933 -> 31253512653248719266062943707325665377464777 -> 46492964703403651468863122584458570244070436 -> 16914079504181797053273763831171860502859028 %Y A292857 Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292846, A292856, A292858, A292859. %K A292857 nonn,base %O A292857 1,1 %A A292857 _Meritxell Vila Miñana_, Sep 25 2017 %E A292857 Terms ordered by _Ray Chandler_, Sep 27 2017