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 A046512 #17 Feb 16 2025 08:32:39 %S A046512 39,47,49,55,57,59,66,68,69,74,75,78,79,86,87,88,89,93,94,95,96,97,98, %T A046512 139,147,149,155,157,159,166,168,169,174,175,178,179,186,187,188,189, %U A046512 193,194,195,196,197,198,227,229,236,238,239,246,247,248,249,263,264 %N A046512 Numbers with multiplicative persistence value 3. %H A046512 Robert Israel, <a href="/A046512/b046512.txt">Table of n, a(n) for n = 1..10000</a> %H A046512 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativePersistence.html">Multiplicative Persistence</a> %e A046512 239 -> [ 54 ][ 20 ][ 0 ] -> one digit in three steps. %p A046512 mp:= proc(n) option remember; %p A046512 if n <= 9 then return 0 fi; %p A046512 1+procname(convert(convert(n,base,10),`*`)) %p A046512 end proc: %p A046512 select(mp=3, [$1..1000]); # _Robert Israel_, Feb 12 2019 %t A046512 mp3Q[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&,n,#>9&]]==4; Select[Range[300],mp3Q] (* _Harvey P. Dale_, May 23 2015 *) %Y A046512 Cf. A003001, A014120, A046503. %K A046512 nonn,base %O A046512 1,1 %A A046512 _Patrick De Geest_, Sep 15 1998 %E A046512 Offset corrected by _Robert Israel_, Feb 12 2019