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 A292856 #19 Jun 27 2025 18:37:23 %S A292856 142710354353443018141857289645646556981858, %T A292856 236547461211163745741763452538788836254258, %U A292856 331948602685207939133668051397314792060866,336111694728585211732663888305271414788267 %N A292856 Numbers k such that 7 applications of 'Reverse and Subtract' lead to k, whereas fewer than 7 applications do not lead to k. %C A292856 There are 7 forty-two-digit terms in the sequence. Terms of derived sequences can be obtained either by inserting at the center of their digits any number of 9's or by concatenating a term any number of times with itself and inserting an equal number of 0's at all junctures. %H A292856 Ray Chandler, <a href="/A292856/b292856.txt">Table of n, a(n) for n = 1..7</a> %H A292856 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 A292856 n = f^7(n), n <> f^k(n) for k < 7, where f: x -> |x - reverse(x)|. %e A292856 142710354353443018141857289645646556981858 -> 715479301293103964616284520698706896035383 -> 331948602685207939133668051397314792060866 -> 336111694728585211732663888305271414788267 -> 426775719443918676633573224280556081323366 -> 236547461211163745741763452538788836254258 -> 615905177676671508625384094822323328491374 -> 142710354353443018141857289645646556981858 %Y A292856 Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292846, A292857, A292858, A292859. %K A292856 nonn,base %O A292856 1,1 %A A292856 _Meritxell Vila Miñana_, Sep 25 2017 %E A292856 Terms ordered by _Ray Chandler_, Sep 27 2017