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 A035931 #14 Dec 30 2019 15:21:19
%S A035931 0,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,3,3,3,3,1,2,2,2,
%T A035931 3,3,3,3,3,4,1,2,2,3,3,2,3,4,3,4,1,2,2,3,2,3,2,4,2,3,1,2,3,3,3,2,4,3,
%U A035931 4,3,1,2,3,3,4,4,3,5,3,4,1,2,3,3,3,2,4,3,4,4,1,2,3,4,4,3,3,4,4,3,1
%N A035931 Number of steps to reach 0 under "k->max product of two numbers whose concatenation is k".
%H A035931 Scott R. Shannon, <a href="/A035931/b035931.txt">Table of n, a(n) for n = 0..10000</a>.
%e A035931 a(341)=5 since 341->123->36->18->8->0.
%t A035931 f[n_] := If[n<10, 0, With[{d = IntegerDigits[n]}, Table[FromDigits[Take[d, k]]*FromDigits[Drop[d, k]], {k, 1, Length[d]-1}] // Max]];
%t A035931 a[n_] := If[n == 0, 0, Length[FixedPointList[f, n]]-2];
%t A035931 Table[a[n], {n, 0, 100}] (* _Jean-François Alcover_, Apr 03 2017 *)
%Y A035931 Cf. A035930, A035932, A035933, A035934, A035935.
%K A035931 nonn,base,nice
%O A035931 0,12
%A A035931 _Erich Friedman_