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 A060630 #12 Aug 13 2020 14:01:06 %S A060630 0,1,10,19,109,149,197,399,694,796,893,897,1167,1579,1596,1667,1790, %T A060630 1777,2859,1779,1778,1873,3679,5926,11289,9539,13551,4589,5960,12066, %U A060630 12265,19119,10927,12379,11742,65220,34038,40390,1110025,10100023 %N A060630 a(n) gives smallest number requiring n iterations of the map i -> A053392(i) to reach zero. %C A060630 24th and 26th terms are unknown, but a(25)=9539, a(27)=4589 and a(28)=5960. %H A060630 Erich Friedman, <a href="https://erich-friedman.github.io/mathmagic/0200.html">Problem of the Month (Feb 2000)</a> %F A060630 a(n)=10^(n-2)+9, for n=2, 3, 4 and for n > 40. %e A060630 a(5)=149 because 149 -(1)-> 513 -(2)-> 64 -(3)-> 10 -(4)-> 1 -(5)-> 0. a(7)=399 because 399 -(1)-> 1218 -(2)-> 339 -(3)-> 612 -(4)-> 73 -(5)-> 10 -(6)-> 1 -(7)-> 0. %Y A060630 Cf. A053392. %K A060630 base,nonn %O A060630 0,3 %A A060630 _Jason Earls_, Apr 14 2001 %E A060630 More terms from Berend Jan van der Zwaag, Jun 23 2001