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 A306569 #10 Feb 26 2019 09:09:08 %S A306569 1,765257552,4858337151,62987487698944,14281197489647865625, %T A306569 16756687971893376,956884714362661,292452281337511936, %U A306569 11897243269649199,1,824281567746336491,13552472793415699584,841944776182612378933,9434962871842528764976 %N A306569 a(n) is the largest value obtained by iterating x -> noz(x * n) starting from 1 (where noz(k) = A004719(k) omits the zeros from k) if any, otherwise a(n) = -1. %C A306569 Is every term positive? %H A306569 Rémy Sigrist, <a href="/A306569/b306569.txt">Table of n, a(n) for n = 1..250</a> %H A306569 Rémy Sigrist, <a href="/A306569/a306569.gp.txt">PARI program for A306569</a> %F A306569 a(10^k) = 1 for any k >= 0. %F A306569 a(10*n) = a(n) for any n > 0. %e A306569 a(2) = max(A242350) = 765257552. %o A306569 (PARI) See Links section. %Y A306569 See A306567 for the additive variant. %Y A306569 Cf. A004719, A242350. %K A306569 nonn,base %O A306569 1,2 %A A306569 _Rémy Sigrist_, Feb 24 2019